NT Labs Pond Salt promotes good health in all fish. Pond Salt has many uses in helping to keep your fish fit and healthy and to help them recover from illness. 1) It minimises the stress on fish. 2) It reduces the toxicity of nitrite in pond water.3) It encourages the formation of the protective mucus layer in winter. 4) Pond Salt adds essential trace elements to the water. Use as a general tonic to help improve colour support the immune system stimulate appetite and supply essential physiological trace elements. Use Pond Salt as a \"liquid bandage\" to help fish with wounds and ulcers recover from treatment. 2.5 kg treats 2500 litres / 550 Gallons