Treating the water that goes into your pond is essential for the safety of your fish and the general health of your pond. Tap water from municipal providers contains chlorine and chloramines, both of which are harmful to fish. To counter-act these chemicals, be sure to use an effective water treatment. Beautiful ponds began with clean, clear water. Algae are a threat to the water quality and health of your pond. They can steal nutrients from the pond's system and choke off the pond's life sustaining oxygen. There're two types of algae that grow in ponds. Single cell algae turn water green and string algae form on water falls and other surfaces. Water rich in nutrient waste products and sunlight is a prime algae growth environment. Simple solutions include feeding only highly digestible foods in the pond and adding aquatic plants to provide protection from the sun. In addition, an EPA approved algaecide will control algae. These algaecides are available in both liquid and block forms. And for continuous control of green algae you can install a UV Clarifier.