Algae bloom is caused by an improper ecological balance in the pond. It feeds on nutrients, sunlight, warm water and carbon dioxide put off by the decay of leaves and fish waste.

Agitating or aerating the water with a fountain or a fall will help remove carbon dioxide from the water.

Oxygenating or submerged plants compete with algae for nutrients.

Even the particular type of algae that causes the green blanket stuck to the walls of your pond are beneficial in competing with the ugly water born algae bloom.

Marginal plants and water lilies help shade and cool the water as do floating plants. One particularly aggressive floating plant is Azzola also known as “Fairy Moss“. It has to be used with great care however to keep it out of natural water systems as it will cover up the entire surface of large bodies of water. You will be adding the maintenance of having to thin it from your pools surface with a net if you choose to add it to your garden. It makes an excellent mulch for the rest of your garden.

Either keep the bottom of your pool clean or do not disturb what lies there as this will mix the nutrients into the water and encourage algae bloom.

Fertilizing:

If you want to fertilize your water plants, use tablets specially made for water gardens. They keep the nutrients at the roots of the plant that you want to benefit rather than feeding algae.

A bio filter once it starts working properly is an effective way to keep algae blooms at bay. It is nothing more than a container with a medium (lava rock works well) for good bacteria to grow in. The good bacteria eats the algae. A bio filter can be hidden inside of a waterfall. Instead of pumping your water into the top of a header pool, just run the pipe to the bottom of the pool and disperse the flow evenly about the bottom (PVC. elbows and tee’s work well for this.) Then cover the plumbing and fill the pool with lava rock or some other porous medium. You can hide the medium you use with a layer of drain rock or gravel.

The down side of a bio-filter is first, that the bacteria takes time to grow and second that the pump can not be shut off even for a couple of hours or the bacteria will begin to die and the waiting process started over.

Once your pond is all properly planted you will need to give it some time to reach it‘s proper eco-balance. It can take several weeks!

Or Not:

If your not into the whole waiting thing there is a fast remedy. A U.V. light of the proper size for the water volume will clear it right up and keep it that way. Other than the costs involved, The unit, pump, electricity and bulb replacements. A U.V. light is hard to beat.

String or Blanket Algae:

String algae is the toughest one to deal with and there is not yet (to my knowledge) an automatic way to keep it away. However there is a lot you can do to prevent it from becoming unsightly. Building your pond with vertical walls will make it mostly un-noticeable. Also building it deeper means cooler & darker water both of which helps reduce algae. A skimmer can help to, not only does it clear off the blanket algae that breaks off and floats to the surface, but a lesser known benefit is that the whole pond stays cooler because it pumps only the water from the surface leaving the deeper water undisturbed and much cooler. Tall marginal plants, water lilies, water hyacinth, and other plants that shade the surface will help. Remember the right amount of string algae is beneficial to the balance of your pond however it will become quite unsightly if left unchecked. If your pond is already installed with less than ideal algae conditions. Don’t fret, There is no gardening chore more fun than playing in the pond! A toilet brush makes a great inexpensive tool for removing it from the pond. It can be easily attached to a pole for those hard to reach places and the algae you remove makes an excellent plant mulch.