The basics of the method I recommend for setting up a marine tank are a two inch layer of sugar-fine coral sand on a bare bottom aquarium and at least 1/2 pound of live rock per gallon. The rock and sand provide biological surface area for bacteria to handle the nitrogen cycle. The surface bacteria (oxygen rich areas) take care of the conversion from ammonia to nitrite and then to nitrate, while bacteria in the depths of the rock and sand where hypoxic (low oxygen) conditions exist, complete the conversion of nitrate to nitrogen gas.

A main circulation of five to seven volumes per hour is typically recommended, but can be less if a wavemaker and pumps is used to establish variable currents in the tank. Variable currents are very important in reef tanks, but less so in fish aquaria. For the simplest of variable currents configuration, I would use a simple lamp timer (48 tripper type) and one powerhead to
counteract the natural circulation set up by main filtration.

A good foam fractionator is mandatory with a circulation rate of at least one tank volume per hour. It is best to use surface extracted water to feed the foam fractionator(s). Fine mechanical filtration isn't necessary and I prefer not to employ any since the circulation of fine particles helps maintain filter feeding organisms in reef tanks. If fresh live rock is putting off large amounts of detrital material, occassional use may be okay. In a fish aquaria, continuous use is an option. Coarse filtration may be necessary to keep fish and inverts out of the foam fractionators and pump intakes.

If this method is being used for a reef aquarium, calcium maintenance is essential. It is typically recommended that a saturated solution of calcium hydroxide (CaOH2), also referred to as limewater, be used to make up all evaporation from the system. It is important that the limewater be at saturation to keep densely populated reef systems adequately supplied with
calcium. To insure saturation, use a minimum of two teaspoons of calcium hydroxide per gallon of water. Limewater should be added via a drip system or other methods that add it over the course of the entire day. Some prefer to add it only at night when the pH is lowest. It is important to monitor pH when using limewater to avoid taking the pH too high. The use of a continuous pH monitor makes this much easier. I used limewater and this same methodology for keeping a fish only tank and the results were excellent. Depending on fish load, a more dilute limewater may be required to avoid taking the pH too high. Calcification in corals is influenced substantially by pH, so maintaining an appropriate pH is very significant.

Use of good quality water with attention to exclusion of nitrate, phosphate and silicates is very important. This quality water should be used for mixing saltwater and making limewater. I use an RO (reverse osmosis) unit with DI (deionization) post filtration. This gives essentially pure water. Although and additional expense, the problems avoided usually represent a cost savings, not to mention the reduction of stress for the aquarist. Where limewater is not enough to keep up with the calcium demand of a reef tank, there are several options. Calcium reactors, though technical seem to be providing excellent results. A two part additive that can be added daily or doses via special doser will maintain excellent alkalinity, calcium and pH. Calcium chloride (CaCl2) can also be used to keep the calcium level above 400 ppm. Calcium chloride lowers alkalinity which requires a buffer to be added. Unfortunately this often results in a see-saw effect between calcium and akalinity levels. If a tank evaporates less than 1% of it's volume per day, fans that encourage evaporation by blowing across the surface of the tank or sump can be used. Maintaining strontium and iodide at natural seawater levels is suggested by most authors.

Lighting of reef aquaria must me a minimum of four full length bulbs that favor the blue end of the spectrum (5500 K or greater) and for tanks deeper than 20 inches, metal halides in combination with florescents is the recommendation. Reef tank lighting varies from four to ten watts per gallon depending on the types of coral being kept. A 12 hour photoperiod is recommended. I wake up the tanks with florescent lighting and then build intensity by using timers to stage in metal halides and additional florescents. If small polyped stony corals (SPS) are contemplated, a five watt per gallon minimum should be seriously considered. A single florescent strip is suitable for fish aquaria, but more can be used if desired, particularly on larger tanks.

Since metal halides and other high intensity lighting produces heat, use of fans to assist in evaporation and to force heat from the lights out of the vicinity of the water, is useful. Pulling heat out of closed filter compartment will also assist in maintaining reasonable temperatures. Tank temperatures of 78 to 82 degrees are most commonly suggested these days.
Minimize the daily temperature fluctuation to about 2 degrees. If submersible motors are used for main and wavemaking circulation, it must be noted that these motors dump their heat to the water. If heat is a problem, using air cooled pumps should help. In areas where air conditioning is not common, a chiller may be required.

Regular partial water changes which add up to 10 to 20% per month are recommended. Early in the life of marine aquariums, siphoning undesireable algae off of the live rock and sand while doing a partial water change, is a useful method of harvesting nutrients that often accompany the introduction of live rock. The nutrients are a result of the death of organisms in and on the rock. Well handled live rock will prevent much of this die-off.Introduction of herbivores early in the life of a reef system will assist in keeping algae problems in hand. Particularly useful are the Astraea tecta snails and Clibinarius tricolor hermit crabs from South Florida. As many as one per gallon can be used, particularly if there is significant algae present.

Good books on the subject of reefkeeping are essential and will pay for themselves in the lives of creatures saved. The best single source book to date is "Natural Reef Aquariums" from Microcosm Publishing by John Tullock. For more advanced reading, "The Reef Aquarium" volume one and two, by Delbeek and Sprung are excellent as is "The Modern Coral Reef Aquarium" volume 1, by Nilsen and Fossa.

5/4/98

Larry Jackson / San Angelo, Texas, U.S.A.
Marine/Reef Consultant
Compuserve's Fishnet Forum