• Free-floating algae is another form of algae that can be found in our ponds. It is what makes the water look like pea soup. It can be controlled by covering 70% of the pond surface with
    plants. You can add
    bacteria and enzymes
    to the pond every
    couple of weeks at a
    cost of around $50 each

  • A UV sterilizer can also be very effective. Note that the tube needs to be replaced regularly (at least every two years), as the tubes have a short effective life even though it may still glow. The best way to control algae is to create a balanced ecosystem.

Every ponder has horror stories about algae. Controlling it is part of ponding. Algae competes with fish for oxygen and competes with plants for nitrates. Uncontrolled algae can choke out other pond life. Despite all the bad press algae does have some redeeming value. It absorbs toxins that would otherwise have adverse effects on pond life and when controlled it serves as a food source when the fish get hungry thus preserving your preferred plants from being nibbled on. Algae can be controlled by depriving it of one of the 4 key elements it needs: oxygen, nitrates, phosphates and sunshine. The easiest to control is sunshine and you can accomplish this by covering 70% of your pond surface with plants. There are two common forms of algae found in ponds: 

  • String algae also known as filamentous algae looks like green string-like cotton candy and attaches itself to rocks and sides of
    ponds. This type of
    algae will be present
    no matter how much
    ​work you do to rid
    your pond of it. It can
    grow several feet long
    and in an unbalanced
    pond it can grow
    quickly - up to 5 inches
    each day. This type of algae will bloom (increased growth) when ever a pond is cleaned and in the spring as the water heats up.  The bloom usually lasts for a couple of weeks before calming down provided the pond has a balanced ecosystem. Removing algae is simple, but only partial, requiring you to use your hands and grab and pull or use a brush. Be careful with a brush on pond liner as you may damage it and cause a leak. Do not use chlorine or other chemicals as they will kill fish and plants. UV sterilizers will not control this type of algae.​