Creating and maintaining a reef aquarium is fun & rewarding.
The following guidelines will help you achieve your goal.
Calcium is the building block for coral skeletons. The skeletons are made of calcium carbonate, which is supplied through the water column. Levels should be at 420 ppm. Coral growth will be limited if levels are below 360 ppm. Calcification will not increase at higher calcium levels, but can cause calcium to precipitate. Calcium is best added as limewater aka kalkwasser.
Alkalinity is of equal importance as calcium because it is composed largely of calcium carbonate. Both, calcium and calcium carbonate, are used for calcification (coral growth). Alkalinity levels should be above 7 dKH. The rate of calcification increases with a higher alkalinity.
Both, calcium and calcium carbonate, can precipitate and usually become dominantly visible on heaters.
The pH level should be adjusted to the needs of the species inhabiting the reef. Calcification slows in low pH conditions. pH should not be higher then 8.0, as higher pH can result in calcium precipitation and therefore lower calcium and calcium carbonate levels.
Magnesium 1300 ppm (+/- 50)
Magnesium inhibits the precipitation of calcium and calcium carbonate, both of which are in a supersaturated state in a reef. Magnesium could be low or rapidly depleted if calcium precipitation is visible; or if calcium, calcium carbonate, and pH levels are hard to maintain.
The temperature influences the solubility of oxygen and carbon dioxide. It also affects the metabolic rate of fish. The temperature should be kept at around 80 degrees.