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FAQ's

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Table of Contents

1. Water (Filters/Additives/Test Kits)
1. Source Water - City Mains Water Is Not Good Enough
1. Background
2. DI Filters
3. RO Filters
4. Further Comments About Water
2. Additives
3. Testable Parameters
1. Alkalinity
2. Calcium
3. pH
4. Nitrate (NO3)
5. Phosphate (PO4)
6. Specific Gravity
4. Water Changes
2. Filtration and Equipment
1. Live Rock
2. Protein Skimmers
1. Counter Current Air Driven Protein Skimmers
2. Venturi Protein Skimmers
3. Protein Skimmer Considerations
3. Granular Activated Carbon (GAC)
4. Other Chemical Filter Media (X-Whatever)
5. Mechanical Filtration
6. Under Gravel Filters (UGF)
7. Reverse Flow UGFs (RUGF)
8. Trickle Filters
9. Algae Scrubbers (somewhat long)
10. Live Sand
3. Lights
1. General Discussion
2. Detail Discussion
3. Lighting Data
4. Cost Estimates
5. Stock
1. Common to Scientific Name Cross Reference
2. Coral Aggression Chart
3. Corals [Cnidaria (Anthozoa)]
4. Shelled Things
5. Algae
6. Possible Problems
7. Hermit Crabs
6. General Catalogs
7. Questions and Answers
8. Book Review
9. Useful Tables
10. Credits

US EPA requirements for water quality from municipal sources are insufficiently pure for reef tank usage. For instance, the EPA standard for Nitrate (as NO3-N) is 10.0 mg/l, over twice the recommended maximum level. Extremely toxic (to inverts) heavy metals such as copper are allowed at levels as high as 1 mg/l.

Most public water supplies have contaminates well below the EPA levels and some reef tanks have done fine on some public supplies. In general, however, it is recommended that some form of post processing be performed on public water before it is introduced into the reef tank.

Although some people have access to distilled, de-ionized or reverse osmosis water from public sources, most will use a home sized system to produce their tank water. The two most common systems used are de-ionization resins, and reverse osmosis membranes.

De-ionization (DI) units come in two basic varieties: mixed bed and separate bed. Two chambers are used in separate bed units, one for anion resins (to filter negatively charged ions), the other for cation resins (to filter positively charged ions). Mixed bed units use a single chamber with a mix of anion and cation resins.

DI units are 100% water efficient with no waste water. They are typically rated in terms of grains of capacity (a grain is 0.065 grams). Once the capacity of the unit is reached it either needs to be replaced or recharged (using strong acids and bases). Recharging is normally only an option for separate bed units.

A quick check of the local water quality charts (normally available free from the water supply company) will reveal the water purification capacity of a given DI unit. For example, if a unit rated at 1000 grains is purchased and the local water supply has a hardness of 123 mg/l (Missouri River, USA), then the unit capacity is (1000*0.065)/0.123 = 528 liters = 139.5 gallons of purified water.

Water production rates for DI units varies, but is typically around 10-15 gallons/hour.

Reverse osmosis (RO) units are normally based upon one of two membrane technologies: cellulose triacetate (CTA) and thin film composite (TFC). CTA based systems are typically cheaper and do not filter as well (90-95% rejection rates). TFC based systems cost more but have higher pollution rejection rates (95%-98%). CTA membranes break down over time due to bacterial attack whereas TFC membranes are more or less impervious to this. CTA units are not recommended for reef tank purposes. RO filters work by forcing water under pressure against the membrane. The membranes allow the small water molecules to pass through while rejecting most of the larger contaminates. RO units waste a lot of water. The membrane usually has 4-6 times as much water passing by it as it allows though. Unfortunately, the more water wasted, the better the membrane usually is at rejecting pollutants. Also, higher waste water flows are usually associated with longer membrane life. What this means in practice is that 300 gallons of total water may be required to produce 50 gallons of purified water.

Like any filter, RO membranes will eventually clog and need to be replaced. Replacement membranes cost around $50-$100. Prefilters are often placed in front of the membrane to help lengthen the lifetime. These filters commonly consist of a micron sediment filter and a carbon block filter. The micron filter removes large particles and the carbon filter removes chlorine, large organic molecules and some heavy metals. Of course, the use of prefilters makes initial unit cost more expensive but they should pay for themselves in longer membrane life.

RO units are rated in terms of gallons per day of output with 10-50 gallon/day units typically available. Note that the waste water produced by a RO unit is fine for hard water loving freshwater fish such as Rift Lake cichlids. Some route the reject water to the family garden. The Spectapure brand of RO units has a good reputation.

The ultimate in home water purification comes from combining the two technologies and processing the water from an RO unit though a DI unit. If a very high grade DI unit is used, water equivalent to triple distillation purification levels can be achieved. Since the water entering the DI unit can be 50 times purer than tapwater, the DI unit can process 50 times as much before the resins are exhausted. This significantly reduces the replacement or recharging cost of the DI unit.

If only one filter can be afforded, and waste water is not a concern, then it is recommended that a TFC RO unit with pre-filters be purchased. If waste water is a concern, or if only a small quantity of make-up water will be required (say, for a single 20 gallon tank), then a DI unit would be the preferred choice.

City water is unstable. Many cities modify their treatment process several times a year, dramatically changing its suitability for reef usage. For instance, Portland has great reef water - most, but not all, of the year.

Calcium (Ca) - required addition. A range of 400-450 ppm Ca++ (10-11 mM) is recommended. The preferred method is the usage of Kalkwasser (Limewater) for all evaporation make-up water. The use of Calcium Chloride (CaCl2) is known to cause problems with alkalinity (provable by balancing the relevant chemical reactions occurring in the tank when CaCl2 is added). Still, CaCl2 is occasionally useful to repair serious Ca++ deficits.

The efficacy of chelated calcium products available for reef aquaria is questionable. To the best of our knowledge, there exists no scientific evidence indicating that chelated calcium is especially available to corals and other CaCO3 depositing invertebrates. Nothing is known about the uptake of chelated calcium products by coral. And most importantly, there exists no evidence showing that chelated calcium products support stony coral growth rates in excess of, or even comparable to growth rates documented in aquaria where calcium is supplied as aqueous Ca(OH)2 [kalkwasser.]

Chelated calcium products also interfere with the ability to measure actual calcium levels in the aquarium. In particular, chelated calcium cannot be measured by any kit which uses EDTA titration, including the highly recommended HACH kit. Some people find the SeaChem kit, which does measure chelated calcium, to be impossible to read with any accuracy.

Until such a time as vendors supplying chelated calcium products make available well conceived, carefully documented uptake and growth studies with their products, or the same experiments are performed and published by third parties, we regard the use of chelated calcium products in the reef aquarium to be experimental at best, especially when kalkwasser and other non-chelated calcium sources are KNOWN to us to support the growth and even reproduction of stony corals in the home aquarium.

Iodine (I) - enhances soft coral growth. It is removed by skimming.

Strontium (Sr) - used rapidly by most hard corals (weekly additions usually performed).

Buffers - increase alkalinity and control pH. Desired range is 2.5-3.5 meq/L (7-10 dKH) alkalinity. Alkalinity can be raised by the addition of one of many commercial buffer compounds. The addition of kalkwasser (saturated Ca(OH)2 solution - also known as "limewater"), which is often done to maintain calcium levels, will also raise the alkalinity level. SeaChem's Marine Buffer, Reef Builder and Kent's Superbuffer dKH are popular. The Coralife and Thiel buffer products have had less favorable reviews.

Iron (Fe) - Used by algaes. Add this if you want good macroalgae growth. Be sure that macroalgae growth is favored or else plaguelevels of hair algae may result.

Copper (Cu) - Used as a medication in fish-only tanks. Copper is highly toxic to invertebrates, even in very small concentrations.

DO NOT USE THIS, IN ANY FORM, EVER, IN A REEF TANK OR ANY TANK WHICH CONTAINS INVERTEBRATES. PERIOD!

Other additives, especially the commercial "secret formula" mixtures, are more controversial. Some people report good results from some of them other people report disaster or no effect. Experiment cautiously with them if desired.

Alkalinity is a measure of the acid buffering capacity of a solution. That is, it is a measure of the ability of a solution to resist a decrease in pH when acids are added. Since acids are normally produced by the biological action of the reef tank contents, alkalinity in a closed system has a natural tendency to go down. Additives are used to keep it at a proper level.

rect alkalinity levels allow hard corals and coralline algae to properly secrete new skeletal material. When alkalinity levels drop, the carbonate ions needed are not available and the process slows or stops.

alinity is measured in one of three units: milliequivalents per liter (meq/l), German degrees of hardness (dKH) or parts per million of calcium carbonate (ppm CaCO3). Any of the units may be employed but dKH is most commonly used in the aquarium hobby and meq/l is used exclusively in modern scientific literature. The conversion for the three units is:

            1 meq/l = 2.8 dKH = 50 ppm CaCO3

[As an aside, there is an imperial unit of alkalinity and hardness which is 'grains per gallon'. The water softening industry uses this unit. 1 gpg = 17 ppm CaCO3.]

A word of caution about the ppm CaCO3 unit is in order. The 'ppm CaCO3' unit reports the concentration of CaCO3 in pure water that would provide the same buffering capacity as the water sample in question. This does not mean the sample contains that much CaCO3. In fact, it tells you nothing about how much of the buffering is due to carbonates, it is only a measure of equivalency.

Alkalinity is often confused with carbonate hardness since both participate in acid neutralization and test kits may express both in either of the three units. However, carbonate hardness is technically a measure of only the carbonate species in equilibria whereas alkalinity measures the total acid binding ions present which may include sulfates, hydroxides, borates and others in addition to carbonates. In natural seawater, though, carbonates make up 96% of the alkalinity so equating alkalinity with carbonate hardness isn't too far off.

Recommended values for alkalinity vary depending on who's work you read. Natural surface seawater has an alkalinity of about 2.4 meq/l. Following are levels recommended by various authors.

From John Tullock (1991) "The Reef Tank Owner's Manual":

page 46 - Alkalinity range should be 3.5 to 5.0 meq/l.
page 94 - Alkalinity reading of 2.5-5.0 meq/l is proper.
page 188- Alkalinity should be about 3.5 meq/l. (In reference to maintaining Tridacna clams.)

Albert Thiel (1989), in "Small Reef Aquarium Basics" recommends 5.35-6.45 meq/l. This is an Artificially high level which may initiate a "snowstorm" of CaCO3 precipitate. Most reef aquarists do not believe in such extreme and unnatural levels and recommend 3.0-3.5 meq/l as a good range instead.

The chemistry of how alkalinity, pH, CO2, carbonate, bicarbonate, and other ions interrelate is fairly complex and is beyond the scope and detail of this document.

Some recommended test kits for alkalinity are the SeaTest kit and the LaMotte kit. The SeaTest kit is very inexpensive and is one of the few SeaTest kits suitable for reef use. The SeaTest kitmeasures in division of 0.5 meq/l or, if the amount of solution is doubled, 0.25 meq/l. The SeaTest kit uses titration in which the acid and indicator are included in the same reagent. The LaMotte kit is a little more expensive, though still fairly cheap, and is somewhat more accurate. The unit of titration is 4 ppm CaCO3 although in practice, one drop from the titration tube may be up to twice this amount making the resolution about 0.15 meq/l. The Lamotte kit has a separate indicator tablet and acid reagent which is a nice feature.

Calcium content is referred to as 'calcium hardness' and is measured either in parts per million of calcium ion (ppm Ca++) or parts per million equivalent calcium carbonate (ppm CaCO3). Calcium hardness is often confused with alkalinity and carbonate hardness since the 'ppm CaCO3' unit may be used for all three. As with alkalinity, a calcium level expressed as X ppm CaCO3 does not imply that X ppm of calcium carbonate is present in the tank; it merely states that the sample contains an equivalent amount of calcium as if X ppm of CaCO3 were added to pure water. The reading also does not tell you how much carbonate is present.

Calcium hardness test kits are different from alkalinity kits. Some people have reported difficulties with the LaMotte calcium hardness kit. The Hach 'Total Hardness and Calcium' kit has not had these reports. Both express results in ppm CaCO3. The relationship between CaCO3 and Ca++ is:

            1 ppm CaCO3 = 0.4 ppm Ca++

The results from a test kit reading in ppm CaCO3 may be converted to the molar concentration scale by dividing by 100.

            100 ppm CaCO3 = 1 mM Ca++

             40 ppm Ca++  = 1 mM Ca++

Calcium levels of natural surface seawater are around 420 ppm Ca++ (10.5 mM). In a well running reef tank you will notice, sometimes dramatic, calcium depletion. Calcium addition in some form is essential. A calcium level above 400 ppm is required and a range of 400-450 ppm Ca++ is recommended. Most reefkeeping books (see bibliography) explain the options for calcium addition.

The suggested reef tank range is 8.0 to 8.3. The pH should hold its own unless alkalinity is low. If alkalinity is OK but pH is low there is probably a buildup of organic acids or a serious lack of gas exchange (low water surface area to volume ratio).

Two units are used to measure nitrates: nitrate (NO3-) and nitrate nitrogen (NO3-N or just N). The ratio is:

            1 ppm NO3-N = 4.4 ppm NO3-.

Nitrates themselves may not be a problem but serve as an easily measured indicator of general water quality. Many hard to test for compounds like dissolved organics tend to have levels that correlate well with nitrate levels in typical tanks.

Different authors cite varying upper nitrate values permissible. No higher than 5 ppm NO3- is a good number with less than 0.25 ppm recommended. Unpolluted seawater has nitrate values below detectable levels of hobbyist test kits, so "immeasureable" is the goal to strive for.

Most test kits measure nitrate-nitrogen. Do not forget to multiply by 4.4 to get the ionic nitrate reading. LaMotte makes a nitrate test kit that will measure down to 0.25 ppm NO3-N. Hach makes one good to 0.02 ppm NO3-N, about 10x more sensitive, but you must be sure to order the saltwater reagents. They will only sell you the saltwater reagents in addition to the regular kit with the freshwater reagents, not in place of them, which is annoying. This makes the Hach kit about twice as expensive in the end as the LaMotte kit but the 10x increase in performance makes this more acceptable.

Phosphates, along with nitrates, are a primary nutrient of algae. Tanks with "high" levels of phosphates tend to be infested with hair algae. All authors cite zero ppm PO4 as a good goal. An upper level 0.1 ppm is recommended by Tullock (1991) with less than 0.05 ppm given by Thiel (1991).

Specific Gravity is temperature dependent. See the next table for a quick lookup of the recommended hydrometer readings. They are based upon our recommended S.G. of 1.025 at 60 degrees F.

   

Degrees F               Hydrometer reading.

   50                   1.0255

   55                   1.0252

   60                   1.0250

   65                   1.0246

   70                   1.0240

   75                   1.0233

   80                   1.0226

   85                   1.0218  (rather hot for most tanks)

   90                   1.0210  (very hot for most tanks)

1.025 recommended for reef tanks. Note that virtually all hydrometers are calibrated for measurements at a temperature of 60 F. Included below is a short table of temperature adjustments. Add the value shown to your hydrometer reading to get an accurate reading.

Degrees F               Correction

   50                   0.0005

   55                   0.0002

   60                   0.0000

   65                   0.0004

   70                   0.0010

   75                   0.0017

   80                   0.0024

   85                   0.0032

   90                   0.0040

For example: If the hydrometer reads 1.0235 at 80F, the actual Specific Gravity is 1.0235 + 0.0024 = 1.0259

Note: If your tank is between 75F and 80F, this means you should try and keep your Specific Gravity around 1.0230 to 1.0235.

For all practical purposes, the scale is linear between data points, so you can simply extrapolate between table entries. For instance, 78F is 3/5 the distance between 75F and 80F; the difference in corrections is 0.0024-0.0017 = 0.0007. 3/5th of 0.0007 is 0.0004. Add the offset 0.0004 to the base value for 75F of 0.0017 and you get a correction value for 78F of 0.0021.

It is fairly common in literature to see references to salinity in terms of Parts Per Thousand (PPT). For salinities in the range we are interested in, the conversion formulas are:

Here is a short table of some common values:

 Salinity                       Specific Gravity

  20 PPT                        1.0135

  25 PPT                        1.0174

  30 PPT                        1.0212

  35 PPT                        1.0251          * Typical Ocean Value * 

  40 PPT                        1.0289

"The solution to pollution is dilution". Water changes are used to correct problems. Minimal changes of 5%/year when all is set up and running smoothly may suffice. Some feel that an occasional water change of about 20% every 1-3 month is a reasonable safety net that may help prevent contaminate buildup and trace element depletion problems. Others recommend 5%-10% per week.

Live rock is simply old coral skeletons that have become the home to multiple small creatures. Typically reef tanks have 1-2 lbs of live rock per gallon of capacity. Pieces vary in size and shape from baseball size to dinner plate size in typical tanks. In large tanks (> 500 gallons) very large pieces of live rock tend to be used. These pieces may individually weight up to 85lbs (about the limit of what one person can handle).

The use of live rock greatly increases the bio-diversity in a tank. However, its primary purpose is to provide a home for bacteria that provide the biological filtration for the aquarium.

Cheap rock has low amounts of coralline algae and tends to grow hair algae well. It may be suitable for a soft coral only tank. Hair algae free coralline encrusted live rock (high quality Florida and/or pacific (Marshall and Tonga Island) rock is highly desirable. "Berlin" style tanks use high quality live rock (and protein skimming) as the primary filtration method with great success.

Required equipment. Don't undersize. Common wisdom is that you can't overskim a tank. Many of the more available commercial units are useful for tanks only in the 10-20 gallon range. Anything shorter than about a foot tall is essentially useless.

Unfortunetly, there is no formula to determine the required size of a skimmer. Amount of organic waste generating organisms (fish, coral, live rock, etc.) will obviously be the primary variable. All skimmers should be filled with TINY bubbles and have a milky white appearance. Any skimmer that doesn't match that requirement is not working optimally.

Two basic styles of skimmers exist: counter current air driven and venturi driven. Both styles work fine, both have tradeoffs. Both require tuning. Expect to spend some time over the first month or so learning how to keep your skimmer tuned. Below is some discussion about the two styles.

These skimmers usually require three pieces of equipment typically not sold with them: an air pump, air stones and a water pump. Total skimmer cost depends upon the kinds of equipment needed to run the skimmer properly.

The water pump injects the water to be skimmed into the unit. Some people use gravity to feed surface overflow water to the skimmer or divert part of the main circulation pump's return flow into the skimmer to eliminate the need for a dedicated pump. Otherwise a powerhead in the sump usually suffices for the water pump.

The air pump must be large enough and a sufficient number of air stones must be driven to make the skimming column milky white. In some skimmers one medium sized air pump like a Tetra Luft G and one air stone will be sufficient. Other skimmers need more to perform optimally. Air driven skimmers should use limewood air stones which will need to be replaced from time to time. Cheap limewood air stones have a reputation of needing to be replaced much more often than high quality stones. Coralife limewood air stones have a good reputation. Air stone replacement rate depends on your tank and skimmer; some people need to change them every 2 weeks others only after 3-4 months.

A.J. Nilsen recommends a 1x tank volume per hour turnover of both water and air by counter current air driven skimmers. Others feel each skimmer has an optimal rate of air and water processing and that if more skimming is desired then more or bigger skimmers should be added rather than trying to operate the current one beyond its optimal performance range.

Some hold that any skimmer under 4' high and 4" in diameter is too small for anything over about a 20 gallon reef.

These skimmers use the Bernoulli effect of the venturi valve to inject air bubbles into the water. This obviates the need of an air pump and air stones. The penalty is that a relatively large, high pressure (read expensive and powerhungry) dedicated water pump is mandatory for the venturi unit to inject sufficient amounts of air.

A particular commercial venturi skimmer may or may not come with a water pump. If it does supply a pump, it may or may not be sufficiently large to run the skimmer properly. At least some of the venturi skimmers easily available are not very well designed.

Venturi valves require occasional cleaning of the air opening. This is as simple as reaming the opening out with pipe cleaner every few days. An acid bath may be required if the unit clogs or gets coated with mineral deposits.

Most venturi style skimmers are more compact that CC skimmers. Manufactures state that they are more efficient, since they (supposedly) inject more air. Many suspect that design constraints (back pressure severely affects venturi performance) have more to do with the manufactured height (who would want a top injected 4' skimmer with air only in the top foot of water?). Properly designed venturi skimmers are tall to maximize air contact time, and require pumps that can handle backpressure.

Below are some pros and cons of venturi vs. CC skimmers. Some people will debate some of the statements.

Venturi skimmers, due to the large water pump needed, have a higher initial purchase price than CC units for the same amount of skimming.

The operational cost of a venturi unit is basically just the electricity bill. A CC unit must sum in electricity consumption for the water pump and air pump (usually small) plus air stone and diaphragm replacement. Which one is more cost effective for you depends upon which equipment you had to buy to run the skimmer properly, your electricity rate and how often air stones need to be replaced. Most people find CC skimmers less expensive to both purchase and operate for the same amount of skimming. Venturi skimmers are less cumbersome in appearance and in operation. They are usually smaller and quieter. They are on the whole more hassle free. The powerful pump required for venturi skimmers may, however, add considerable heat to the water.

One general note on water pumps: The amount of heat added to the water varies by brand, design, usage, and placement. Basically, the more efficient the pump (gallons delivered at a given pressure for a given power usage), the cooler it will run. Restricting the output of the pump will generally increase the water temperature. (Never restrict the intake of a centrifugal pump!) Obviously, an air cooled pump will increase your tank temperature less than a submersible (and therefore tank water cooled) pump will.

Some debate about its usage. Most use it at least a few days a month, some continuously. Many brands have problems with phosphate leaching.

X-Nitrate, X-Phosphate, Polyfilters, Chemi-pure, etc. - probably not needed in established, balanced reef aquaria. A prominent manufacturer of these materials was either unwilling or unable to supply capacities for removing the named compounds from seawater. May cause adverse reactions in some inverts.

This is an area of interest currently being debated. Originally the FAQ stated:

Good idea to pre-filter skimmer water. Floss works fine and is cheap and disposable. Sponges work well, but require cleaning twice a week or so. Natural sponges with a medium fine or fine pore size are recommended. Some people don't use mechanical filtration, allowing detritus to settle in places for removal by siphoning. Some of these people make dedicated "settling tanks" to trap debris in a convenient place. Julian Sprung suggests not pre-filtering skimmer water as skimmers will remove particulates (rather than trapping them as a pre-filter would do). Spotte confirms this and terms this filtering mechanismas 'froth floatation'.

Many members of the group of authors do not use mechanical filtration. They believe that such systems filter out the plankton that is used as food by many marine organisms. Some members use "live sand" setups, with detrivores. Others routinely siphon accumulated detritus.

Use of a mechanical filter for short periods may help when attempting to resolve specific problems, such as a hair algae outbreak.

Not appropriate for a Reef Tank. Although they will work for 6 months or so, eventually detritus buildup will cause a nitrate problem. Long term, it's virtually impossible to keep nitrates below about 40 ppm NO3- which is way too high for corals.

An attempt to solve the detritus buildup problem associated with normal flow UGFs. It's a good idea that doesn't work well in practice. This system has problems with uneven water flow due to channeling within the bottom gravel.

Also known as Wet/Dry Filters. An improvement over UGF and RUGF filters. Nitrates can be kept low (say, around 5 ppm) with adequate water changes. It does not seem to be possible to keep nitrates very low (less than 1 ppm) if a trickle filter is the sole biological filtration. Those that report less than 1 ppm normally have adequate live rock, and find that their Nitrates remain low even (and often get lower) when they remove all the bio-material from their trickle filters (turning them into plain sumps, useful for holding carbon and as a water reservoir).

Summary: the jury is still out. May help, may hurt, not currently recommended, especially as the sole filter. The topic is controversial. Below is some discussion about it.

In most healthy natural communities, particularly coral reefs, dissolved nutrients are scarce. In aquaria, by contrast, nutrients in the form of dissolved inorganic nitrogen, or DIN, (a collective term for ammonia, nitrites, and nitrates) accumulate very rapidly as fish and other organisms excrete these wastes. The most basic problem in any aquarium is limiting the accumulation of DIN.

In reef aquaria, DIN is consumed by the community of organisms on the live rock. It is uncertain what relative contribution is made by bacteria as opposed to algaes, but it is certain that the live rock community as a whole can remove a substantial amount of DIN from a reef aquarium. In fact, it is quite possible to run a reef tank with no biological filtration (DIN consumption) other than that which takes place on the rock. This method is part of what is now known in the United States as the "Berlin school" of reefkeeping.

Other schools of thought utilize additional biological filtration in separate filters. Traditional reef tanks supplement the filtration provided by the reef (often not acknowledging the role of the reef itself) with bacteria-based trickle filters. Many readers probably learned this technique first, as it has been the dominant method in the United States amateur hobby for some time. Yet another approach uses algaes, which are also capable of utilizing inorganic nitrogen directly. An algae filter, or algal scrubber as it is usually called, is simply a biological filter which utilizes a colony of algae rather than bacteria as consumers of inorganic nitrogen.

Algal scrubbers are not new; they are discussed in Martin Moe's (1989) excellent _Marine Aquarium Reference: Systems and Invertebrates, for example. However, algae filters have been regarded in the past as too bulky and inefficient to be the sole filter for a aquarium. The recent surge of interest in algal scrubbers seems to have been generated by Adey and Loveland's book _Dynamic Aquaria_ (1991). They discuss both techniques which allow an algal scrubber to be compact and efficient and also a number of arguments as to why they are preferable to other filtration methods.

One reason to use an algal scrubber according to Adey and Loveland is that it mirrors the way DIN is cycled in nature. They claim that perhaps 70-90% of the DIN in reef communities is consumed by algae, rather than by bacteria. The two methods produce rather different water chemistry; for example, algae are net producers of oxygen and remove carbon dioxide, while a bacterial filter consumes oxygen and produces carbon dioxide. They argue that it should be easier to maintain the type of water chemistry found over a natural reef by relying on an algal scrubber.

Also, algae remove the nitrogen from the water in order to build tissue, while filter bacteria simply put it into a less toxic form. The excess nitrogen can be removed completely by periodic algae harvests, while dissolved nitrogen in the form of nitrate is not as easy to remove. Adey and Loveland claim that their methods can bring levels of DIN down to a few hundredths of a ppm, far below (in their opinion) the levels reachable with other methods. A related argument in favor of algal scrubbers is that stability in natural ecosystems seems to come from locking up nutrients in biomass, not in allowing it to be free in the environment. An algal scrubber does precisely this, while a bacterial filter converts it to free nitrate dissolved in the water. A final reason to use an algal scrubber according to Adey and Loveland is that many other kinds of filtration (including protein skimmers) remove plankton from the water. An algal filter naturally does not do this, and can actually provide a refuge for some forms of plankton. The importance of this effect is, however, a matter of some debate.

As compelling as some find the above arguments in theory, there seem to be serious problems with algal scrubbing in practice. Many attempts by public aquaria at implementing reef tanks using only algal scrubbing have been failures. In particular, it seems difficult to find successful long term success with Scleractinia (stony corals) in such tanks, and those success stories which can be found are quite difficult to verify and often contradicted by others.

Various public and private aquaria have used algae scrubber filters on their reef aquaria, with disastrous results. The microcosm at the Smithsonian Institution has yet to keep scleractinia alive for more than a year. While Dr. Adey has stated how well corals grow in this system, those viewing the system have failed to find these corals. In an interview with Jill Johnson, one of the techs responsible for the Smithsonian tank, she stated to Frank M. Greco that frequent collecting trips were needed to keep the system stocked with live scleractinia.

The Pittsburgh AquaZoo also has a "reef" tank based on Dr. Adey's algal scrubbers. This tank is nothing more than a pile of rocks covered with filimentous green algae, and the water is QUITE yellow (as is the Smithsonian tank) from the presence of dissolved organics (ORP readings have been around 165). As with the Smithsonian tank, scleractinia do not survive longer than a few months. The same applies to soft corals as well. When I (Frank M. Greco) saw this tank on May 3, 1993, there were NO living corals to be found even though a collecting trip to Belize was made several months earlier and 81 pieces of living scleractinia were brought back. There were, however, two piles of dead Atlantic scleractinia: one right behind the tank and the other in the greenhouse housing the algal scrubbers.

The Carnegie Science Museum (Pittsburgh, PA) also uses an algal scrubber system, but with significant modifications. This tank looks the best of the three. There are several species of hardy Scleractinia and soft corals that are doing quite well. The water is clear (a bit cloudy). The major differences between this system and the other two is the use of carbon, a small, barely functioning algal scrubber, about 1000 lbs. of excellent quality live rock (Florida), water changes, and the addition of Sr and Ca.

The last system I know of that uses an algal scrubber is the Great Barrier Reef Microcosm in Townsville, Australia. As of this writing, the system is not maintaining live Scleractinia, and frequent collecting trips are needed in order to replenish the exhibit. It should also be noted here that while Dr. Adey has claimed in his book Dynamic Aquaria that corals have spawned in this system, what he doesn't mention is that the corals which spawned were collected only months before the known spawning season. From these few examples, it should be clear that algal scrubbers are NOT to be used in systems containing live scleractinia.

Possible reasons why algal scrubbers seem to fall short center around the observation that it seems difficult to control hair algae growth in scrubbed aquaria. Hobbyists have for many years seen their stony corals slowly pushed back off of their skeleton and killed by encroaching algaes, and much effort in the hobby has been devoted to controlling this growth. Only with strict control of algaes does coral survival seem possible. Most or all reefs with algal scrubbers seem to have heavy algal growth in the tank as well, which the experience of the hobby suggests is incompatible with stony coral survival.

The main method used by hobbyists to restrict algal growth is to reduce nutrient availability; in fact, the claim that other methods cannot reach the same low levels of DIN achieved by algal scrubbing is probably not true. Advanced hobbyists are beginning to use better tests, such as HACH's low level nitrate test, and are finding that they can achieve nitrate levels below 0.02 ppm. Berlin methods seem particularly able to reach these levels, which are comparable to that on natural coral reefs.
If low nutrient levels can be achieved by both methods, then why is algal growth a much greater problem with scrubber methods? The answer is not known, but there are two factors which probably contribute.

First, the discussion so far has mentioned only inorganic nitrogen. Algaes seem to release much of the inorganic nitrogen which they take up in the form of dissolved organic compounds (DON), which can also be later utilized by algaes. The very low levels of DIN measured in scrubbed tanks may mask the very high levels of DON which persist, providing nutrients for strong algal growth. This is borne out by many reports that the water in scrubbed tanks often has a pronounced yellow cast, characteristic of dissolved organic compounds. Since the water over natural reefs is very low in DON, high levels may be directly harmful to many corals, in addition to promoting uncontrolled algal growth.

Another possible effect of algal scrubbing is more subtle. Algal growth is never completely halted in any marine tank, merely reduced to the point where macro- and micrograzers can keep them in close check. The net rate of new growth depends not only on the availability of nutrients, but also on the amount of existing algal growth releasing free-floating cells into the water to colonize new sites. Even if the rate of growth of individual algal colonies is equal, a scrubbed tank has a growth of algae in the scrubber much larger than a reef tank with little algal growth anywhere in the system. This possibility suggests that the presence of the scrubber itself and not merely high levels of DON is an obstacle to the successful long-term maintenance of stony corals.

The weight of evidence at this point seems to be against the use of algal scrubbing in reef tanks, and the method should be considered to be highly experimental. Beginners particularly are advised to avoid this technique until they have considerably more experience with reefkeeping. The advanced aquarist may well wish to experiment with this interesting and controversial method, but it would be unwise to risk the lives of an entire reef tank full of coral. Such experiments should progress slowly, beginning with the most hardy of inhabitants. Many of the objections center on stony coral survival, and it is possible that scrubbed tanks with fish and hardy invertebrates may do quite well.

Of relatively recent interest in the hobby is the use of "live sand". Live sand consist of small grain (0.5mm-1.0mm) coral sand that is populated with crustaceans and bacteria. It is normally used at a rate of 10lbs per square foot of bottom area - which yields about a 1" deep covering. Variations from 1/8" to 3"s of covering have been reported.

If you decide to have a live sand substrate bottom, you should include several creatures that will turn-over, or otherwise, move the sand around. Recommendations include: Sea Cucumbers, Brittle Starfish, Serpant Starfish, Golden Headed Sleeper Gobies, Yellow Jawfish, Watchman Gobies, and other detrivoirs. A mix of the above is recommended, since each creature moves the sand around differently.

Live sand has a reputation of eliminating the final traces of nitrates in otherwise well run tanks. It also provides an environment for additional bio-diversity in the tank. Additionally, some feel that the chemical balance and stability of a tank's water is improved when live sand is present.

Note that live sand usage should still be considered experimental. Usage is dependent upon have the sand sifted and otherwise moved around to prevent detritus from accumulating. Many people have reported problems keeping their turn-over creatures alive for long periods of time. Some have not seen the reported nitrate reductions. Keep in mind that many reef tanks have operated for years without a substrate and have no detectable nitrate concentrations.

A rough "rule of thumb" is 4 Watts/gallon with successful tanks using from 1.5 - 6 Watts/gallon.

Fluorescent fine (some prefer) for shallow (<20") tanks. Use mix of bulbs (50-50, 03s, etc.)

Metal Halide (MH) required for deeper tanks.

Mercury Vapor, Halogen, HPS, etc. - avoid, wrong spectral output
.

For most aquarium lighting applications, the bottom line is getting the needed intensity and spectrum of light at the lowest cost while remaining within aesthetic limits.

A lighting analysis is now presented. Everyone has their own sets of numbers they would plug in here, for now lets assume the following for comparison. Many will debate specifics found below. Feel free to substitute your own numbers, but the methodology is sound.

NO lumens per lamp = 2600 (Phillips F40D daylight, initial)
NO watts per lamp = 40 (ditto)
NO cost per lamp = ~$20 (from memory, DLS actinic day)

VHO lumens per lamp= 5940 (Phillips F48T12/D/VHO daylight, initial)
VHO watts per lamp = 110 (ditto)
VHO cost per lamp = ~$30 (ditto)

MH lumens per lamp = 36000 (Philips MH400/U, initial)
MH watts per lamp = 400 (ditto)
MH cost per lamp = ~$70 (from memory, Venture 5200K)

operate lamps 12 hours/day
replace lamps once per year
electricity cost = $.09 / KWH (your mileage may vary)

Annual cost per lumen:

cost = ( cost-per-lamp / lumens-per-lamp )
+ ( watts-per-lamp / lumens-per-lamp ) * 12 * 365 * .09 / 1000

NO cost = .0077 + .0061 = .0138 dollars per year per lumen
VHO cost = .0051 + .0073 = .0124 dollars per year per lumen
MH cost = .0019 + .0044 = .0063 dollars per year per lumen

Basically, in fluorescents, the VHO lamps give a higher operating cost but a lower replacement cost for the same total amount of light. But it's close, and you should plug in your own numbers to see what's best for you. If you replace lamps more frequently then VHO is better, if you pay more for power, NO is better. There is a greater variety of lamps available for NO than VHO. OTOH, it seems that NO lamps can be operated at VHO power levels, with a somewhat shortened lifetime (the higher replacement frequency is offset by lower lamp cost), so this may not be an issue.

The initial installation cost (basically the ballast cost) is higher for VHO, even in terms of per-lumen, but this is a pretty small part of the total cost of the lighting system over the years.

NO requires more lamps for a given total light intensity, so you may not be able to fit enough NO bulbs in your hood if you need a lot of light.

MH seems to be a winner in both replacement and operating costs, but there are a couple of caveats. The math ignores the effect of the ballasts on power consumption, whereas I've measured fluorescent power consumption as less than the lamp wattage (even on conventional transformer ballasts) and MH power consumption as slightly higher than the lamp wattage. The other caveat is just the EXTREMELY limited choice of spectrums for MH, which is why few people use MH without any fluorescent.

MH vs fluorescent also gets into the aesthetic and biological considerations. Water surface ripples causing light ripples in the aquarium and room are pronounced with MH lighting. Many people appreciate this effect. Some (e.g. Julian Sprung) feel the variation in light intensity is actually important for some photosynthetic organisms. Many people are under the impression MH runs hot, whereas fluorescent doesn't. In reality, the efficiencies are similar, with MH producing slightly LESS heat than the equivalent fluorescent. The difference is MH dumps all the heat in a small space so the local temperature rise is greater. But if you want to try to get rid of the heat it's actually easier to do it if the heat is concentrated in one spot, since its easier to get rid of a small amount of very hot air than a very large amount of warm air.

A separate issue, so far only applicable to fluorescent, is the selection of a conventional ballast vs an electronic one. There is no doubt the electronic ones are more expensive to purchase, but the savings in electricity offset the high initial cost in a year or so. Also, if heat production is an issue, the electronic ballasts are to be favored. The Icecap VHO electronic ballast is widely advertised, however its advertised claims are also frequently questioned. Advance makes a series of NO electronic ballasts.

There are yet two more issues, for which there are a lot of questions and too few answers. Specifically, the short term flicker in light intensity, and radiated electromagnetic fields. Fluorescent lamps on conventional ballasts flicker at 120 Hz, which is above the human visual response, so we don't see it (actually, the flicker is both in intensity and spectrum). But that doesn't mean other creatures can't see it, or whether they benefit or are disadvantaged by it. Electronic ballasts cause flicker at ~30 KHz; it is seriously doubtful that any creature can detect this, so it would appear constant.

The flicker doesn't have to be visible to have an effect: it causes any movement to appear strobed, and this may affect the feeding efficiency of visual hunters.

The fields issue is even more obscure. At least many cartilaginous fish (sharks, rays, etc) are known to be extremely sensitive to electric fields, and many crustaceans are sensitive to magnetic fields (crabs with pieces of magnetite in internal sensory organs). Fluorescent lamps, with the large area they cover, tend to radiate (using the term pretty loosely) fairly strongly, but MH, and the wiring, and the ballasts can radiate too. It's unknown on how significant this could be in an aquarium (but its known sharks preferentially attack undersea cables because of the fields, so there is at least indirect evidence its an issue worth some thought).

BTW, a grounding device reduces the level of induced voltages in the tank, but this is achieved at the expense of increased induced current, so its effect (if any) may depend on the species. Also, note if you have a titanium coil chiller on the tank, it is probably already grounded through the chiller, and an additional ground may in fact increase the electric current. This should not be an issue with epoxy or ceramic coated chiller coils.

FILE|WATTS|MANUFACTURER|DESCRIPTION      |HOURS      |TYPE      |

T1   400   IWASAKI      6500K                          M/H

T2    20   LIGHTSOURCE  UVB                            FL

T3    20   LIGHTSOURCE  UVB WITH FILTER                FL

T4   400   VENTURE      4000K                          M/H

T5   400   VENTURE      4000K WITH FILTER              M/H

T6   400   SYLVANIA     4000K             2400 HOURS   M/H

T7    60   CHROMALUX                                   TUNGSTEN

T8    40   CORALIFE     50/50                          FL

T9    40   ACTINIC SUN                                 FL

T10   40   PHILLIPS     ACTINIC 03        3650 HOURS   FL

T11   40   PHILLIPS     ACTINIC 03                     FL

T12   40   RAINBOW      PRIMETINIC                     FL

T13   40   RAINBOW      FLORA_GLOW                     FL

T14   40   RAINBOW      BIO_LUME                       FL

T15   40   TRITON                         3650 HOURS   FL

T16   40   DURALIFE     POWER TWIST                    FL

T17   40   HAMILTON     SUPER ACTINIC     3650 HOURS   FL

T18   40   PKILLIPS     ULTRALUME         3650 HOURS   FL

T19   40   PERFECTO     PERFECTALIGHT                  FL

T20   40   SYLVANIA     350EL BLACKLIGHT  3650 HOURS   FL

T21   40   SYLVANIA     350EL BLACKLIGHT               FL



nm      T1      T2      T3      T4      T5      T6      T7      T8      T9

280             0       0                                               

290             0.00369 0                                               

300             0.01136 0                                               

310             0.0173  0                                               

320             0.01326 0                                               

330             0.00725 0                                               

340             0.00366 0                                               

350     0.00928 0.00126 0       0.00173 0       0.01344 0.00156 0       0

360     0.01185 0.00155 0       0.03944 0       0.07642 0.00071 0.00012 0.00011

370     0.02    0.00199 0       0.03428 0       0.07363 0.00166 0.00115 0.00104

380     0.03036 0.0007  0       0.0043  0       0.03063 0.00361 0.00086 0.00075

390     0.0446  0.00084 0       0.01287 0       0.05199 0.00574 0.00422 0.00329

400     0.07903 0.00544 0.0014  0.07214 0.01949 0.14805 0.01098 0.02255 0.01686

410     0.08931 0.0058  0.00188 0.06103 0.02356 0.1331  0.01644 0.05968 0.04407

420     0.16201 0.00126 0.00076 0.01713 0.01747 0.06811 0.02291 0.08731 0.06047

430     0.09997 0.01352 0.01175 0.13073 0.13383 0.2202  0.02654 0.09023 0.06469

440     0.08765 0.02331 0.02023 0.1601  0.1598  0.2264  0.03179 0.0736  0.05465

450     0.07976 0.00053 0.00041 0.01077 0.01184 0.04449 0.03795 0.02631 0.02099

460     0.12665 0.00078 0.00072 0.00687 0.00716 0.03796 0.04864 0.01588 0.01347

470     0.15064 0.00074 0.00069 0.01622 0.02078 0.07935 0.06293 0.01061 0.00931

480     0.16282 0.00071 0.00066 0.01501 0.01751 0.07474 0.08342 0.01361 0.0122

490     0.262   0.00081 0.00075 0.01746 0.01798 0.07031 0.10565 0.02889 0.02518

500     0.1875  0.00074 0.00069 0.01715 0.01926 0.07363 0.11878 0.01326 0.01125

510     0.1742                  0.03241 0.03973 0.12924 0.11684 0.00561 0.00456

520     0.1746                  0.01067 0.01085 0.06063 0.11877 0.00424 0.00337

530     0.1903                  0.01495 0.01622 0.06525 0.11566 0.00658 0.00568

540     0.2163                  0.2472  0.2453  0.3389  0.17133 0.0945  0.08678

550     0.2249                  0.3589  0.3569  0.4931  0.2222  0.10093 0.08811

560     0.1535                  0.01939 0.02075 0.07519 0.2276  0.00777 0.00829

570     0.1721                  0.15115 0.15653 0.2859  0.11034 0.00485 0.00444

580     0.2015                  0.4783  0.47    0.6035  0.04333 0.02203 0.0205

590     0.11089                 0.1499  0.10326 0.4279  0.04889 0.02291 0.02103

600     0.13418                 0.015   0.01253 0.07882 0.15686 0.01332 0.01218

610     0.12794                 0.01226 0.01103 0.0517  0.2926  0.07374 0.06906

620     0.14258                 0.02842 0.0302  0.10766 0.3906  0.04382 0.03969

630     0.13358                 0.03349 0.03673 0.10084 0.4227  0.02397 0.02217

640     0.11311                 0.014   0.01398 0.05127 0.4511  0.00603 0.00571

650     0.09402                 0.01115 0.01077 0.04064 0.4742  0.00692 0.00652

660     0.10513                 0.01143 0.01088 0.04971 0.4899  0.00584 0.00544

670     0.085                   0.01551 0.01315 0.08427 0.4922  0.00403 0.00386

680     0.08657                 0.01111 0.01079 0.03203 0.4808  0.0037  0.00358

690     0.09202                 0.01929 0.01898 0.03834 0.4944  0.00411 0.00377

700     0.08359                 0.00975 0.01033 0.03056 0.5355  0.00286 0.00277

710     0.04801                 0.01305 0.01273 0.02949 0.5522  0.00911 0.00917

720     0.05045                 0.01045 0.01025 0.03059 0.5485  0.00149 0.0014

730     0.04745                 0.00957 0.00941 0.0182  0.4476  0.00042 0.0004

740     0.04609                 0.00985 0.00964 0.02177 0.2395  0.00041 0.00039

750     0.04023                 0.00983 0.00959 0.01954 0.2498  0.00037 0.00035



nm      T10     T11     T12     T13     T14     T15     T16     T17     T18

350     0       0       0.0001  0       0       0       0       0       0.00011

360     0       0       0.00167 0       0       0       0.00144 0       0.00147

370     0       0.00016 0.00087 0.00119 0.00126 0.00145 0.00196 0       0.00133

380     0.00011 0.0007  0.00063 0.00027 0.00017 0.00023 0.00145 0.00011 0.0007

390     0.00403 0.00563 0.00399 0.00033 0.00012 0.00018 0.0021  0.00155 0.00066

400     0.01468 0.0379  0.02569 0.00377 0.00299 0.0037  0.00745 0.02094 0.00546

410     0.04403 0.12285 0.07521 0.00446 0.00432 0.00611 0.00952 0.08984 0.0083

420     0.06681 0.1955  0.12078 0.00138 0.00651 0.00983 0.0078  0.15751 0.00904

430     0.06231 0.1714  0.13584 0.01281 0.03371 0.03597 0.02406 0.14212 0.03191

440     0.04237 0.10573 0.1221  0.0229  0.0599  0.05814 0.03307 0.08825 0.04797

450     0.01287 0.03535 0.05784 0.00225 0.04818 0.04703 0.0128  0.03013 0.02376

460     0.00567 0.01538 0.03935 0.00271 0.04462 0.05381 0.01496 0.01326 0.02429

470     0.00268 0.00698 0.02608 0.00332 0.03433 0.0541  0.01834 0.0061  0.02294

480     0.00125 0.00319 0.02679 0.00396 0.02981 0.05097 0.02108 0.00287 0.03173

490     0.00082 0.00195 0.05095 0.00486 0.03909 0.04972 0.02354 0.00178 0.05773

500     0.00062 0.00051 0.02319 0.00537 0.02092 0.03006 0.02579 0.00056 0.02643

510     0.00037 0.00073 0.00728 0.00672 0.01013 0.01802 0.02974 0.00079 0.01024

520     0.0003  0.00056 0.00496 0.00985 0.00732 0.01111 0.03445 0.00064 0.0078

530     0.00027 0.00049 0.00645 0.016   0.00668 0.01075 0.03592 0.00056 0.013

540     0.00623 0.01053 0.13192 0.03586 0.07958 0.0697  0.04315 0.00846 0.1921

550     0.01079 0.0185  0.1251  0.05488 0.07655 0.06983 0.04723 0.01463 0.1743

560     0.00028 0.00038 0.01025 0.04627 0.00731 0.0088  0.02902 0.00035 0.02394

570     0.00061 0.00085 0.00549 0.05201 0.00444 0.00586 0.02876 0.00069 0.01534

580     0.00314 0.00569 0.03686 0.0556  0.02172 0.0227  0.032   0.00446 0.04439

590     0.00039 0.00047 0.03892 0.04418 0.01716 0.02913 0.02544 0.00044 0.04907

600     0.00013 0.00051 0.01518 0.04409 0.00375 0.02508 0.0284  0.00036 0.03261

610     0.00126 0.00136 0.09569 0.04722 0.01159 0.16014 0.03433 0.00087 0.14292

620     0.0009  0.0015  0.06356 0.05247 0.04658 0.07106 0.03533 0.0013  0.08503

630     0.00057 0.00087 0.0269  0.06004 0.06313 0.03852 0.03461 0.00084 0.04806

640     0.0003  0.0006  0.00674 0.05213 0.05384 0.0087  0.03259 0.00043 0.01323

650     0.00025 0.00047 0.00797 0.07652 0.1192  0.01039 0.0305  0.00036 0.01485

660     0.00026 0.00049 0.00564 0.10016 0.1775  0.00799 0.02782 0.00039 0.01222

670     0.00023 0.00043 0.00554 0.04559 0.06493 0.00461 0.02474 0.00035 0.00851

680     0.0002  0.00039 0.00499 0.02232 0.01908 0.00396 0.02155 0.00031 0.00761

690     0.00032 0.00056 0.00425 0.01701 0.00976 0.00639 0.01861 0.00047 0.00787

700     0.00022 0.00041 0.00348 0.01193 0.00434 0.00551 0.01536 0.00032 0.00583

710     0.00041 0.00077 0.01145 0.00964 0.00302 0.01905 0.01322 0.0006  0.01719

720     0.00022 0.00049 0.00167 0.00712 0.0013  0.00286 0.01038 0.00034 0.00305

730     0       0.00013 0.00044 0.00546 0.00072 0.00068 0.00827 0       0.00054

740     0       0.00012 0.00045 0.0044  0.00059 0.00075 0.00685 0       0.00098

750     0       0.00013 0.0004  0.00352 0.00045 0.00071 0.00559 0       0.00093



nm      T19     T20     T21                                             

300                     0                                               

310                     0.01441                                         

320                     0.00473

330                     0.01484

340                     0.03041

350     0       0.01513 0.02693

360     0.0001  0.01831 0.03403

370     0.00144 0.01491 0.02582

380     0.00097 0.00948 0.01617

390     0.00474 0.0052  0.00903

400     0.00806 0.00633 0.00942

410     0.01157 0.00532 0.00778

420     0.01243 0.00154 0.00258

430     0.02928 0.01093 0.01555

440     0.0403  0.01854 0.02698

450     0.0223  0.00053 0.00163

460     0.0258  0.00069 0.00137

470     0.02929 0.00061 0.00124

480     0.03084 0.00057 0.00072

490     0.03039 0.00076 0.00119

500     0.02779 0.00063 0.00101

510     0.02431 0.00037 0.0007

520     0.02064 0.00029 0.00056

530     0.01756 0.00028 0.00048

540     0.02217 0.00924 0.00974

550     0.02535 0.01594 0.01769

560     0.00816 0.00029 0.00033

570     0.00725 0.00062 0.00081

580     0.0119  0.00497 0.00639

590     0.00888 0.00044 0.00042

600     0.00953 0.00035 0.00037

610     0.05257 0.00111 0.00114

620     0.03046 0.00129 0.00145

630     0.03244 0.00082 0.00089

640     0.02281 0.00047 0.00047

650     0.04607 0.00035 0.00037

660     0.06831 0.00039 0.00038

670     0.02469 0.00033 0.00034

680     0.00813 0.0003  0.0003

690     0.00567 0.00046 0.00047

700     0.00362 0.00031 0.00032

710     0.0071  0.00062 

720     0.00146 0.00033 

730     0.00059 0       

740     0.00052 0       

750     0.00045 0

ALL DATA CONTAINED WITHIN IS COPTRIGHT 1994 BY FRANK M. GRECO (baldbruce@aol.com) AND TO BE USED ONLY WITH PERMISSION OF ONE OR BOTH OF THESE PEOPLE.

Here is a rough estimate of what setting up a reef tank may cost. Two cases are included: a 20g micro-reef and a 70g mini-reef. The estimates show the min and max for most of the common pieces of equipment. The estimates assume a standard type of filtration that is popular today. If a different setup is used, the price could be more or less. The equipment includes a tank with some sort of siphon/drain to a sump and then a return pump back to the tank. A protein skimmer is installed in the sump. This setup is similar to a typical wet/dry trickle filter except there is no trickle section with media. This allows the use of simpler, less expensive sump although a commercial W/D without media could be used. A trickle media could be utilized at greater cost although many reefkeepers think it is unnecessary. Keep in mind that prices sometimes vary geographically. Also, availability may vary. For example, reasonable Florida live rock may soon no longer be available (at least not for $2-4/lb)
.

The estimates include the cost of the initial set-up. There is also a section on ongoing costs. The ongoing cost will vary greatly, especially considering that you will stock your tank gradually. Keep in mind that you always end up spending more than you think you will. If you set up a reef, you will end up stopping at the hardware store and/or aquarium store for timers, extensions cords, GFIs (a must!), buckets, hoses, and books, don't for forget books. You should read a few books on reefkeeping before even planning your setup. An extra hundred bucks or three is going to leak out of your wallet whether you plan on it or not. Another factor is that more advanced equipment may translate into less or easier maintenance. You should keep in mind that if you go with inferior equipment, maintaining the tank will be more work. More expense will mean more automated equipment and less work. Also, some varieties of inverts require more exacting condition, more light, etc. Plan your purchases so that the stock you buy has a chance of surviving with the equipment you are using. If you have a bare minimum system, stick hardy items like soft-corals, polyps, mushrooms, etc.

The minimum included is close to rock-bottom as far as an acceptable systems goes. It assumes that you are DIYing much of the equipment as cheaply as possible. The maximum in the estimate is in some areas a little extravagant but not unreasonable. A good system that is not extravagant could be put together for somewhere in between the two extremes. Perhaps, for 1.25 to 2 times the minimum, you would have a very nice system. Some areas are easier to cut-corners on than others and some of the initial cost may be incremental, like buying test kits as needed. Also, you may have some of the equipment already from previous set-ups or be buying it used. Seek out the advice of an experienced reefkeeper then planning and pricing your system.

MicroReef (20g)

Tank            $  20/ 140      Glass/

                                Acrylic.

Stand               0/ 250      Sturdy piece of furniture/