Coral Pro Salt has been specifically formulated for use with "mineral free" reverse osmosis, or soft tap water and contains the elevated levels of calcium and buffer capacity that provide the extended availability of these elements, essential for vibrant coral growth.Chemically balanced formula to support the most delicate corals and other marine lifeReaches a stable, natural pH shortly after mixingFree of nitrates & phosphatesProduced by a small batch process to ensure homogeneity and consistency of the salt mixture48.4 poundsProduces 175 gallons of saltwater