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Why is my water green? How Can I Solve the Problem?

Water is usually green because of floating algae. Algae need three things to live: sunlight, air, and nutrients. Algae live off of organic waste in the water, which comes from fish waste, decaying plant material, decayed bugs, and other stuff that naturally falls into the pond. If you have an overload of organic waste that is not efficiently being removed by aquatic plants and beneficial bacteria you will have algae. Too much fish food, decomposing leaves, pollen and dust can contribute to the abundance of nutrients. Anything organic turns into fertilizer for algae as it decomposes.

Adding plants to your pond will not only add beauty but they will help to combat algae. Their nutritional requirements are the same as algae and roots from the plants will take a lot of the organics out of the pond. Floating plants such as hyacinth will help greatly as they have large root systems that hang right in the water eating up the algae food! We also recommend adding water lilies to ponds which do not have an abundance of big koi in them (big koi eat lilies). Lily leaves should cover approximately 60% of the surface are of the pond. The leaves provide shade, which will help to keep the algae in check. There are other benefits to adding lilies such as beautiful flowers and cooler water but these are for another FAQ!

Another requirement for clear water is beneficial bacteria. Well-colonized bacteria will out-compete the algae for the nutrients in the pond. Many factors contribute to the inability of the bacteria to take care of excess nutrients. A new pond may not have enough bacteria established to efficiently remove nutrients. Given time, the problem will take care of itself. Or you can add bacteria to jump-start your colonization. Once the bacteria deplete the nutritional value of the organic matter, the water clears up quickly, often overnight. Beneficial bacteria need something to cling to and to grow on. Biological filters, stream beds filled with rocks, and AquaMats can provide the space for bacteria to colonize.

We recommend regular applications of live bacteria. Bacteria can be added in a powder or liquid form. Beneficial bacteria will naturally inhabit your pond but you will get a better rate of growth of the bacteria if you will add it to the pond.

A high pH prohibits the natural bacteria from growing properly. The pH should be in the range of 6.5 to 7.5 for normal growth of bacteria. High pH often contributes to green water and excessive string algae growth.

Lastly, there are algaecides for the pond. These products are chemicals and should be applied following label instructions closely. An overdose of algaecide can cause fish and plants to die. However, some people swear by algaecides for their ponds, especially for string algae.