Saltwater Aquarium Maintenance
You should buy, as well as a nitrite test kit, a pH test kit. This issued in the same way, measuring the pH of water samples by their effects on colored dyes. The kit will contain acid and alkaline solutions which can be used to adjust the pH to the optimum 8.0to 8.3 level. Once the tank is properly matured, pH seldom varies much, but it may become more acidic in a long-established tank. To avoid such problems, it is sensible to change 25 per cent of theater every two months, replacing it with water (of the proper SG) prepared in your plastic dustbin.
Maintain clinically clean conditions, removing every scrap of uneaten food or debris. Algae will grow on the coral and glass, and need not be removed unless they become too unsightly. Alter-natively, reduce the lighting level a little or shorten the period of artificial lighting each day.