A two-part solution for replenishing calcium and alkalinity. Adjusts calcium, magnesium and strontium ions to Natural Seawater ratios, and achieves a balanced ionic residual. Promotes the optimal conditions for stony corals and coralline algae. The 1 gallon size is a concentrate, sold 1/3 full. The user adds reverse osmosis water to bring the liquid level to the top, making a full strength solution for both parts. The dealer can also do this as a service for customers.