ive been looking for a filter for my pond, yet as its only small, all the filters for sale seem far too big (and expnsive) is it possible to make a filter? if so how would i go about it?
use the idea and build of these to make your own all you need is a plastic box (like them stacking ones with lids) have an inlet at the top at one end and an out let at the bottom at the other end and feed it off a pump in your pond, fill the box up with bio balls (or simular) and different grade sponges that would work
In a gravity filter the pump pushes the water into the filter at the bottom, the water rises up through the media and then it flows back out through the outlets at the top and back down into the pond
I've sunk 3/4 into the ground so there is only about 30cm above ground but the plants hide it & the outlet pipe is about 15cm above the pond water level.
You can use your favorite bio-media I used 80 pot scrubbers plus bio-media & sponges from the old filter, the wadding is used to polish the water when needed.
This was my attempt at a pond filter: http/www.howyoubuildit.com/PondFilter/index.html .
It works really well. I have it connected to a 100 gallon pond.
I will shortly build a second one for my brothers pond.
Hope you find it useful