Masterpet Water Ager, 50ml. Makes tap water safe for bowls, aquariums, ponds. Water supply in most New Zealand towns is treated with chlorine to reduce the transmission of harmful bacteria organisms. However, chlorine is deadly to fish. Water ager helps neutralize chlorine, and makes water safe. Disinfectant buckets and buckets for other household uses may retain chemicals that could kill your fish. Use a separate container. A 20% water change weekly will help keep fish fit and healthy. Treatment, 2 drops per litre.