Why Has My Pond Turned Green?

Green water is caused by single-celled algae which tend to bloom from the start of spring until the end of autumn. These blooms coincide with the increase in light levels as single-celled algae are photosynthetic, meaning they gather energy from sunlight.

Although being rather unsightly, algae is actually a benefit to a pond as it helps to balance the carbon dioxide and oxygen levels whilst consuming waste nutrients such as nitrates and phosphates.

In fish ponds, algae is generally undesired as it prevents you from viewing your livestock.  Fortunately, there is a solution to green water issues by installing a UV Clarifier inline with your filtration system.  The UV Clarifier will irradiate the algae cells destroying their outer membrane, causing the algae cell to burst and then flocculate (clump together) to enable your pond filter to trap them.

For this to work effectively you will need to firstly ensure the UV Clarifier is suitably sized for your pond volume.  Also, ensure the pump is delivering water at the most effective rate through the UV Clarifier and that you are turning the pond over at least once every 1.5 hours.  Algae has the ability to replicate itself roughly every two hours so you need to cycle the entire pond volume before it gets an opportunity to multiply.

If your pond doesn't have a filter or pump there are still ways to prevent single-celled algae blooms but they are generally less effective and more repetitive treatments.  Flocculant agents can be added to clump algae cells together and these clumps can then be easily netted off the surface of the pond.  This will need repeating on around a weekly basis to ensure clear water throughout the spring/summer period.  Algaecides and targeted pond water treatments can also assist in preventing algae growth, algaecides act by rupturing the cell causing it to burst.  Different varieties of algae require different types of algaecides. 

If you need assistance in selecting a UV Clarifier, pond treatment or just need advice on a water quality issue, get in touch with the team at Water Garden Ltd.