Treats 500 gallonsThis unique balanced formulation of essential physiological salts promotes fish health all year round.It improves water quality with its built in pH buffer which guards against potentially damaging swings in pH.Pond Guardian salt helps fish to maintain a stable internal salt and fluid balance, which is essential for fish health.It will help minimize stress in fish and act as a supportive treatment when treating disease.Pond Guardian salt also reduces the toxicity of Nitrite, a toxic fish waste which can build up in the pond.