Silicate occurs in tap water or purified water when the reverse osmosis or deionizing unit is not functioning properly. Silicate can result in diatom bloom and can block some essential trace elements such as vanadium and molybdenum. The Salifert Test kit for silicate is a quick, sensitive and accurate test, with two scales: an ultra-low scale which is particularly useful for marine water and a high scale which is suitable for freshwater environments. Enough for 60 tests. Can be used for marine, fresh and garden pond water.