Why is my pond Green?


There are two types of algae you can get in your pond.

  • ‘Pea Soup’ Green Algae – This algae is a suspended single celled organism that is so tiny that is passes through your filtration.
  • Filamentous Algae – This algae comes in a few different forms. It can grow in stringy clumps throughout the pond or cling to the sides of the pond or waterfalls and rocks that are present.

Having Algae in your pond doesn’t mean you have done anything wrong, it’s a completely natural factor in the ecosystem you have created. No pond should be algae free. Fish absolutely love the water being ‘Pea Soup’ green and will generally spawn better in it and you will have a better chance of any fry surviving in the pond.

If you have just set up a pond and you have found the water has just gone completely green within the first couple of months this is nothing to worry about. New ponds will generally go green until there is an ecological balance established. Just having a bit of patience with it and helping it along by adding Clarifier Bacteria will help move it along. If you wish to have your pond cleared up without waiting for the pond to sort itself out then there are treatments available to help with this. The worst thing you do is empty it out and start again. It will only come back worse and you will be getting rid of any good bacteria that is trying to start-up.

If you have an established pond that has gone green then, again, this is nothing to worry about. There are many factors that will effect why your pond has suddenly started blooming algae. Some of these factors you can control. These include:

  • Plants – Algae feeds off of the excess nutrients in the pond which is produced by the breakdown of the decaying organic or inorganic matter present. Plants in the pond eat these nutrients as well and they will compete with the algae, slowing its growth.
  • Feeding – Making sure you have a high quality fish food will reduce the growth of algae and making sure not to overfeed the fish is important. Any uneaten food should be scooped out otherwise it will encourage the algae to thrive.
  • Manual Cleaning – Some people find that they have algae growth due to the amount of leaves and debris falling into their pond. You can help prevent this by putting pond netting over the pond or scooping out any leaves with a fish net.
  • Treatments – There is a range of water treatments that will help to clear the pond water or get rid of that filamentous algae. These treatments come in natural or chemical forms.

Treatments for ‘Pea Soup’ Green Algae:

If you are having continuous problems with the water going green the absolute best way to prevent this is with a UV light. This is an external unit that is easy to connect to the pump system you may already have, otherwise UV lights generally come standard with an external filter system. Some Short-term treatments include:

Treatments for Filamentous Algae:

If you have any questions on these products and which one would best suit your pond environment don’t hesitate to give us a call on (08) 9250 6063, shoot us through an e-mail sales@thepondshop.com.au or visit us at 39 Farrall Road in Midvale.