Some of the main causes of excess algae are too many fish for size of the pond because excess fish waste can feed algae as will over feeding your fish as the food waste decays and feeds algae.  Pond plants can absord nutrients that feed algae so having a good coverage of pond plants is beneficial.

Make sure you allow beneficial colonies of bacteria to build up on rocks, bio filters and the gravel in the pond. Over cleaning a pond can cause more harm than good by greatly reducing the beneficial bacteria growing on the filter mats, bioballs and lava rocks.

Too much sunlight can exacerbate the issue of filamentous algae, this can be helped by adding plants. Fertilizers used in plants around the pond can wash into the pond with rain and runoff.

The two types of algae that most pond owners and water gardeners experience are the suspended planktonic algae that makes the water greenish and the string algae that often grows in warm stagnant areas around rocks and in waterfalls.

Planktonic algae consist of millions of microscopic algae floating throughout the water. This causes the water to turn green or “pea soup” color. Filamentous algae or string algae forms long and short hair-like strands. It attaches itself to rocks, gravel, plants, or any surface area it can find in the pond.

While algae is different from more traditional pond plants, they are still plants, and just like other plants, algae require the same elements to grow: sun, food and water.  The best way to fight algae is ensure proper conditions in the water, reduce the sunlight and available food using proper filters, pumps and algae control products.

Algae can help balance the food chain ponds but all it takes is a slight shift in balance and algae can start to take over. Using beneficial bacteria and products like Pond Balance, D-Solv9 and Biological Clarifier are good ways to quickly restore a pond. Barley straw extract and pellets are also good natural sources of algaecide that will not harm fish and wildlife.

Algae in ponds can leave the water green or cause filementous strands to form on rocks, waterfalls or even float on the surface. Maintaining proper filtration is key to keeping water clear. The build-up of fish food, leaves, muck and any other organic waste can cause algae to form in ponds.

There are a range of specialized treatments that can be added to water to help control and eliminate existing algae. The ionizer systems are effective and easy to install and they simply connect to your existing pump system and release ions into the water which keep waters from turning green. Oxygen based algaecides can be sprinkled on algae matts and waterfalls and will quickly eliminate hairlike algae strands.

UV clarifiers are very effective at keeping water clear but adding products to combat problem algae is often required.