Pre Filter Installation


This is a 15kl Koi pond. A typical old style filter installation, been working like this for years. Pond is clear and not heavily stocked with 12 Koi of around 50cm in size.


Cracked or split sand filter

As you can see the old filter is starting to come apart at the seams, literally. As algae builds up in the pond so the pressure in the filter builds and over time this happens.


Typical pressurised filter installation

Ugh. The bio filter on the left has been added almost as an after thought. The pond and this installation is around 15 years old though so this is fairly typical for the thinking back then.


Prefilters installed

This is a temporary installation. The prefilters will have a concrete base cast under them to support them properly and the intention is once the sand filter is decommissioned to add an additional biofilter behind the pre filters and to move the existing bio filter to the same location. We are constrained by the fact that there are only two 50mm returns back to the pond.


Prefilters installed


Prefilters installed

The completed picture. Two 800mm pre filters installed in parallel. We will run the system like this for about two weeks before bypassing the sand filter. After that an assessment will be made.



A week later the slab has been thrown:

Pre filter installation concrete base