What you need to know about UV filters for ponds

Does your pond look like pea soup?

So, your pond has the “pea soup syndrome”? And you have finally decided to do something against the algae crowding it?

Or, maybe you want to reduce the risk of disease pathogens in your pond, to avoid trouble with your fish and plants?

In both cases a UV pond filter is a superb solution to your problem. This article outlines all the basics and essentials you need to know.

How do UV filters for ponds work?

When water is pumped from your pond through the UV filter, the single-celled algae are exposed to very high levels of ultra violet light. This destroys their DNA and causes the algae to divide. And when they divide, they die, resulting in them clumping together.

These clumps of dead algae can then be removed from the water.

A UV pond filter is NOT a ‘filter’

Technically, a ‘UV filter’ is not a filter, because it doesn’t physically remove the dead clumps from the pond.  It only kills the free floating algae, and is usually called a ‘clarifier’ or a ‘sterilizer’.  You still need a filter along with it. So from now off on in this article, we’ll be referring to these UV pond filters as “UV pond lights”.

What kind of filter do you need to get rid of the dead algae?

There are two options:

  1. The simplest: you can use a mechanical filterto get the dead matter out. Well, rather, YOU get the stuff out by backwashing and cleaning the filter.
    In the beginning when you start using the uv light in the pond you have to regularly do this. When the water becomes less green, there will be less algae to clear out and thus the filter will remain a lot cleaner.
  2. You can also use a biological filter. Instead of physically removing the dead algae and other bio matter from the water, these are trapped in a tank that contains beneficial bacteria. And it’s these ‘good’ bacteria that decompose the organic waste materials.

For more on the difference between a mechanical filter and a biological filter see this article (coming soon).

Where do you place the UV light?

The obvious: The UV light is placed