Factors that help limit algae are shade, aeration, lower water pH, and the proper plant-to-fish balance. If you have a filter, it should be cleaned daily.
Are your ponds natural or ornamental? Algae thrive in the shallow, warm water of small ornamental ponds, and sunlight increases the water temperature. Algae feed on decaying leaf litter which can fall into an ornamental pond from trees in the landscape.
Do you have fish in your pond? If yes, you may have more fish than your pond can support. The general rule is that each square foot of water surface area can support a 2-inch long fish. If you have fish and feed them more than they can eat, the algae eat the leftovers.
Do you have plants in your pond? Some potting soils can muck up pond water; heavy clay is a better alternative. A mix of submerged, marginal, and floating plants is beneficial. The floating plants reduce the penetration of sunlight into the water and subsequently reduce the water temperature. Submerged plants, also known as oxygenators, compete with algae for nutrients.
One of the latest developments in the world of algae control additives is barley straw. Some good algae act as a food source for critters living in your pond.
Please refer to the following website for more information: Water Gardening.
