Guide for saltwater aquariums

"The key to success with a saltwater aquarium is keeping it simple," says John Deason, owner-designer of the manufacturing company Captive Sea. "If I had my way, every client would have only one fish, because like anything else, when you have more than one you don't give it enough attention."

Saltwater aquariums aren't difficult to maintain, says Mr. Deason, and take about the same amount of care as freshwater ones. But there are some common mistakes to avoid, he says:

1. Putting fish in too soon.

The chemical balance needs time to get established. Once the proper pH level and the salinity, nitrate, and ammonia balance are reached, add one or two small fish such as damsel fish. Waste from the fish has to be consumed by bacteria in the sand, but the bacteria doesn't start to grow until there is waste. So start slowly and let the bacteria build.

2. Using too many fish.

Don't overload the aquarium. The general rule is 1 inch of fish per gallon of water. For compatibility have fish mostly the same size.

3. Overfeeding.

Avoid the attitude of "the poor things are so skinny, they need a lot of food." By overfeeding, the fish will either eat too much or they won't eat all the food put in the aquarium. Surplus food rots, polluting the water. Be conservative.

4. Polluting the water.

Window cleaner and other solvents with ammonia in them can poison the water if used near the aquarium. The air pump pulls air from the room up through the aquarium, so any cleaning sprays or insecticides used in the room can get into the water. When using extermination gases, move the aquarium out of the room or seal if off and shut off the pump. Air the room out before you turn on the pump. It won't hurt to have the pump off for two hours or so.

5. Changing the water.

Never drain a saltwater aquarium. Change maybe 10 percent of the water per month. If all the chemical levels test out perfectly, don't change it at all. Draining all the water destroys the bacteria the helps maintain the system.