Any tap water used in aquatic environments should first be treated to ensure it is suitable for use and will not harm your fish. Blagdon Tap Safe is a water conditioner designed to treat tap water and make it safe for use with pond fish. Chlorine and heavy metals found in tap water is damaging to fish skin and gills. These harmful toxins are removed from the water and protective colloid aloe vera is added for extra protection and care for your fish.Blagdon Tap Safe is suitable for new ponds or for after pond cleaning and water top ups. Contains toxic waste reducing Pro Biotic active bacteria and 125ml treats upto 2273 Litres.