TMC Marine Salt provides top quality salt for marine systems, and is used in all TMC fish houses. This is a top of the range salt, and is ideally mixed with RO water to provide the best for your marine systems. It has a high dose of calcium and magnesium that will ensure corals take all that they need from the water, essential for strong coral formations. With this salt being Phosphate and Nitrate free its ideal for somone who are having algae problems.