Recommended Ranges
Before getting into problems and solutions, let’s first define what constitutes a problem and what does not. Based on published studies3 involving the calcification of corals and other organisms, I recommend the following:
Alkalinity2 (due to bicarbonate and carbonate but not borate, so those using Seachem salt must raise this value substantially to accommodate the borate being counted in standard alkalinity tests)
2.5 - 4 meq/L or 7 - 11 dKH or 125 - 200 ppm CaCO3 equivalents
Calcium:
380 â€"œ 450 ppm calcium ion or 950 - 1125 ppm CaCO3 equivalents