HAD-A-SNAIL is used to eliminate unwanted snails in freshwater aquariums. It does not kill snail eggs and treatment should be repeated in two weeks to eliminate newly hatched snails. HAD-A-SNAIL must be used in hard water (32 p.p.m.) only. It will not upset the biological system in the aquarium and can be used with most fish and live plants when applied as directed. A 3/4 ounce bottle treats up to 400 gallons of aquarium water.