the CS Test for Chlorinity by Coral Shop is the first kit we have seen to specifically measure Chlorinity in aquarium water. Chlorinity is a measure of the Chloride, Bromide and Iodide ions that make up the total dissolved solids of an aquarium. Although Chlorinity is constant in relation to the salinity of natural seawater, in our aquariums the Chlorinity can get quite out of whack with synthetic salt mixes, two part dosing, balling and all sorts of additives being cut with Chloride ions. The effect of imbalanced Chlorinity is one of the first chemistry problems that novice reef keepers often face when they keep adding CaCl to the reef hoping for the Calcium to rise but the huge pool of Chloride ions prevents proper Calcium adjustments. The effect of imbalanced chlorinity is particularly important for power users of two-part solutions and balling methods where there is a high potential for Chloride to build up. The Coral Shop Test measures Chlorinity from 0-50 grams per liter (g/l) with an accuracy of 0.25g/l and a single kti can perform up to 50 tests. If you are a baller or power user of two part and other liquid additives, it may be worthwhile to add the Chlorinity test kit to your chemistry set. The testing and management of Chlorinity should be reserved for intermediate to advanced aquarists with a decent understanding of basic marine aquarium chemistry. Thanks Karl.