Koi Rescue
Phoenix Arizona



Shortypen Barrel Filter 3




This is actually about the 10th or 11th different configuration of a barrel filter that I have tried, but it is the 3rd one that I have made a web page about. It works pretty good and solves some problems I discovered with previous versions.

Please note that there are MANY ways to create a filter for your koi pond. I am just trying to illustrate the types of filter configurations that I like.


This one is hooked up to a quarantine tank that I keep adoption koi in.

A submersible pump is in the tank, and that pumps to the top of the packed column aerator (tower pipe) which you pump the pond water into. The water drops through that tower and is aerated by wiffle balls inside the pipe.

As the water enters the barrel, it turns and heads across the surface of the bioballs. In previous filters, I sent the water to the bottom of the barrel and had it flow upwards. A problem emerged that since the surface of the water was fairly still, mosquitos would lay their eggs in the filter and it became a mosquito factory. I read that mosquitos won't lay their eggs in moving water, so I switched to pumping water across the surface of the bioballs. Tried it and it works! No more mosquitos in the filter.

The water will swirl around in the barrel, go through the bioballs and then it heads out the return pipe.

The return pipe on the outside of the barrel goes back to the pond. If you are going to run a large amount of water flow through it like 1500 gallons per hour, you need to have the end of the pipe under the surface of the pond water so it creates a siphon. The siphon really does helps pull the water out of the barrel.

Another thing you can do is adjust the angle which the return pipe goes into the pond. This tank is perfectly round, so it can build up a fast current if I have the pipe pointing more horizontal. To reduce the current, I have the pipe pointing mostly down.

Here is a close up of my return pipe strainer. It is just a piece of 2" pvc that has a bunch of lines cut in it.

An important point is that the return pipe is a Tee, so that if the strainer lines get clogged, the water will overflow and head out the return. If you don't have an overflow, then it can clog, and all the pond water will spill out of the filter, draining your pond.

Backflushing the barrel is easy, I have a submersible pump that I just leave in there all the time. I have it on a switch, so what I do is shut off the main pump, then turn on the backflush pump and stir the bioballs as it drains. If it gets really dirty, I fill and drain the filter like this a couple of times.

Normally I backflush all of my filters atleast once a week. Sometimes twice a week if they are looking extra disgusting.

I'd suggest you use a large pump for your backflushing, like a Beckett 1000 gallon per hour pump. It will make the backflushing chore go a lot faster, and if your main pond pump ever died, you can just swap out your backflush pump to use as the main pump.

For filling the tank, I have a sprinkler water timer and valve permanently hooked up, and have a hose over to the filter.