Calcium is not the only substance needed to form the skeletal material of corals and allow calcareou * The total carbonate and bicarbonate concentration is also called alkalinity or carbonate hardness an * The Salifert test is sensitive enough to detect small changes in levels of alkalinity, measuring in * Sufficient for 100 to 200 tests. * The Salifert KH + pH buffer additive makes correction of the alkalinity or carbonate hardness simple