Dosing Alkalinity and Calcium in a Reef Tank

Water changes alone supply enough alkalinity and calcium for many light-to-moderate coral loads. When tests show alkalinity dropping more than about 1 dKH per week despite regular changes, supplemental dosing or a calcium reactor may be needed.

Two-part liquids must be dosed to consumption — test, dose, retest. Large single doses spike pH and stress corals. Dose in small amounts away from corals or into a high-flow area.

Never dose without testing. Log dose amounts and test results the same day in ReefDiary; guessing is how tanks swing from 6 dKH to 11 dKH in forty-eight hours.