Salifert test kits are the epitome of accuracy and precision. Their wide range of available tests have all been designed to detect the smallest traces of certain elements, without interference from other chemicals within the water. Simply put, these are the best test kits you can buy- hands down. The sharp, contrasting color changes make results easy to read so there's no second guessing. Trust your aquarium to Salifert. This calcium test will detect the smallest fluctuations of calcium in saltwater reef aquariums so you can be sure your corals and other invertebrates are receiving an adequate amount for their general health and growth. This item not available for backorders.