Koi Rescue
Phoenix Arizona

ShortyPen Barrel Filter 1

I tend to cram a lot of fish in a small space, and so doing need a LOT of filtration. I researched a BUNCH of different filter configurations and came up with this type of barrel filter, it borrows ideas from a number of different ones and combines it all together.

This filter is fairly ugly, but it works really well, is simple & cheap to build, and combines the functions that ususally takes several seperate parts:
- trickle tower - for aeration
- protein skimmer - to help seperate small particles
- vortex seperator - settle and seperate big particles
- upflow wet bio filter - for biofiltration
- waterfall return - extra aeration step

The following photos and text show the 30 gallon filter I made for the adoption tank, I did the same for the big green stock tank but used a 55 gallon barrel and larger pipe instead.

First is to start with a plastic barrel. This one is a 30 gallon that I got for free from a car wash. You can also use a trash can.

Start off by making the water return. The black bulkhead thing is a shower drain for a fiberglass shower. It costs about $6 from Home Depot. The neck accepts a 2" piece of pvc pipe, which you can then put fittings on to make the w

Most koi ponds need a high turn over rate for their filters. I have heard various flow rates that you can get thru DIY barrel filters and wanted to see what a good flow rate was, and the maximum I could get using these 2" shower drains as bulkhead fittings. I pumped various flow rates of water into the barrel to see what was the most I could flow thru with a gravity return. I found that 1000 gph seemed like a comfortable rate. At 1350 gph, the water level rises above the water return by a few inches. At 1500 gph, the water overflows the top of the barrel.

One way to increase the flow rate would be to add a 2nd shower drain, or add a regular bulkhead fitting of larger size.

This is what the other side of the shower drain looks like.

Now make the trickle tower. I used a brick and a piece of plywood.

Drill holes in the side of the pipe, about 6" up from the bottom. When the water exits the pipe, the lower part of the barrel ends up being a setting area and debris and stuff will stay down in the bottom.

The tower pipe is setup along the outside perimeter of the barrel.

With the barrel dry, fill it up to a level 6" under the water return. The reason is that bioballs just barely float, so when filled with water, the balls will rise and create a cavity in the bottom. The holes in the side of the tower pipe makes the water spin, and preso you have a vortex / settling chamber.

Fill the tower pipe with bioballs and it will tear the water apart as it falls, and really aerate it. You can also suspend something in the pipe a few inches above the water line to create an extra drop. I used a wiffle ball on a string.

Next setup your pump to drop the water in the top of the pipe. You can't see it very well, but the part that drops the water into the tower pipe is a PVC to garden hose connector. This makes it super easy for me to do water changes, I just take the pipe out and screw a garden hose to it.

For the adoption tank, I setup 2 tower pipes and run 2 seperate pumps.

This photo is after some of the koi spawned in the adoption tank and made a mess. The tower pipes makes the water foam, which rises to the top of the bioballs and the foam pops, leaving debris over the top layer of balls.

For cleaning the bottom of the barrel, make a stick of PVC pipe to siphon the water out. I turn the pump off, stick the pipe down in the barrel, attach the garden hose, then spray water backwards up the hose.

The PVC stick bubbles a bit then stops bubbling -- at which time I stop spraying water in the hose, and it immediately starts to siphon the water from the bottom of the barrel. I use a seperate stick to adjitate the balls to loosen up the muck between the balls.