How To Change A Fish Only Aquarium Into A Reef Aquarium

caniThe aquarist running a fish only aquarium has gained a great deal of valuable knowledge about husbandry. He/she has also been able to keep fish that the reef aquarist cannot. These fish are considered as not ‘reef friendly.’

This is the first consideration before any move is made towards a reef aquarium. The aquarist will know the fish being kept – are they reef friendly? If there is any doubt then research is needed. Chances should not be taken. If the aquarist cannot bear to part with any fish then either the aspiration for a reef aquarium should go, or a reef aquarium should be set up separately.

Let’s assume the aquarist has all reef friendly fish. There will be further consideration of these fish later.

In the fish only aquarium seawater quality is important. In the reef aquarium, seawater quality is very important. For the reef nitrate needs to be 10 parts per million (ppm) or less, and phosphate 0.03ppm or less. Of course, ammonia and nitrite should be undetectable. If the fish only seawater is to these standards (unlikely perhaps) then the aquarist can maintain the reef. If not, then increases in amounts or regularity of routine water changes may need to be considered, and the filtration method also.

The recommended filtration method for a reef aquarium is live rock. This should be applied at around 1½ lbs per gallon in the system. This live rock can be purchased as ‘base’ rock and surface ‘premium’ rock, which doesn’t hit the pocket quite as hard. If the fish only system was filtered by a ‘wet/dry’ method, or by canister filters, then consideration should be given to changing. Filtration can be by these methods, but it not as reef effective, and it is probable that nitrate and phosphate will rear their unwanted heads, causing the aquarist to require additional equipment to deal with the pollutants. Many fish only systems are filtered with live rock. In this case, is there enough?

Looking toward water quality, is a sump in use? This is not an inescapable requirement, but is a great move toward maintaining high water quality when a deep sand bed (DSB) is employed, and also perhaps algae filtration (Caulerpa). If a sump is not in use, consider using one. Have the aquarium drilled for the overflows to feed the sump, and obtain a return pump that will move the system gallonage through the sump around three times an hour.

No doubt the aquarist has a good idea of what type of corals are to be kept, soft or hard. At this point, lighting needs consideration. With the fish only aquarium, perhaps two fluorescent tubes have been used. This is inadequate for any common coral type.

Soft corals can use fluorescent tubes. The best practice is to fit as many tubes down the length of the aquarium as possible, ensuring they are fitted with reflectors. The tubes should consist of at least two actinic blue tubes, and the rest should be marine white, assuming a minimum of four tubes. The tubes can be of the T5 type. The order of fitting should be blue, white, white, blue. Where there is space, an equal number of blue and white should be fitted (ie. blue, white, blue, white, blue, white). The aquarist will probably be using an electric timer for the lights on the fish only system. An additional timer is required, so that the blue tubes come on ½ hour before the whites, and go off ½ hour after the whites. This gives a ‘dusk/dawn’ effect. The white tubes should be on between 9 and 12 hours per day. The blue tubes stay on all the time from switch on to switch off, this is because they are not just there to create the ‘dusk/dawn’ effect, but they assist the corals as their light spectrum suits the zooanthellae algae in the coral tissues.

Hard corals normally require halide bulb lighting of the appropriate power for the depth of the aquarium (they come in 150, 250, 400 watts etc). If the aquarium is very shallow, 15″ or less, then T5 tubes as described in the previous paragraph may do, but the hard corals may need placement towards the top of the reef. Halide bulb(s) are really the way to go with these corals. For a 3 ft aquarium one bulb will suffice, for a 6 ft two, and so on. Use bulbs of a 10 Kelvin to 14 Kelvin spectrum. Select the correct power bulb(s) to suit the depth of the aquarium. Also use one, or preferably two, T5 actinic blue fluorescent tubes as described above. Also use electric timers to switch the tubes and halide bulb(s) on and off also as described above.

In the soft coral reef water movement should be chaotic and non-directional as far as possible. As a very general guideline, powerheads can be successful and should have the ability to move the display aquarium water about ten times per hour.

In a hard coral reef, water movement needs to be stronger, and the ability of the power heads needs increasing to move the display aquarium water at around twenty times per hour.

Never allow the outlet of a powerhead to hit a close-by coral.

Water movement can be created by wide or narrow outlet power heads, and the aquarist should research this.

Another consideration for a hard coral reef is the availability of calcium. On a large aquarium it is best to consider a so called calcium reactor, which will constantly supply calcium to the reef (hard corals in numbers place a considerable demand). This is done by using a dissolving media within the calcium reactor, which will also supply some other trace elements. With a small aquarium, calcium can be added by using supplements in careful doses strictly according to the manufacturer’s recommendations.

The aquarist will already have test kits, probably for pH, nitrate, nitrite and ammonia. These are fine for the reef system. However, attention has also to be paid to alkalinity, calcium, magnesium and phosphate.

Now to the fish again. The fish held are all reef friendly. There is one more consideration, and it might be painful. This again involves the high water quality that is so important. The reef aquarium cannot support the same number of fish, gallon for gallon, as the fish only system can. The aquarist will know the net gallonage of the system. This will support one inch of fish (excluding the tail) for each 6 gallons of seawater. If the fish already stocked present an excessive load, the aquarist will have to choose which to keep and which to let go. Not much fun, but necessary. The aquarist who has now added a sump may well think that it isn’t necessary as the sump has added more gallons. There are more gallons, but these are not taken into consideration in the calculation, I’m afraid. The seawater in the sump is extra and aids water quality. It is the seawater in the display aquarium that is considered.

So there we are. The conversion is quite straightforward with some research thrown in.

There is much to recommend the fish only system, with the beauty of the fish, and the fact that reef unfriendly types, such as many butterfly fish, can be stocked. But is there anything that can rival a healthy mixed reef system?