DIY Project — Aquaponics Pump Filter

Okay, I’ll level with you. My aquaponics system is not really low tech. This is my first foray into growing plants from fish excrement, and so I consider it a proof-of-concept project. In the future, I plan to build a large-scale, wind-powered aquaponics set-up (described in yesterday’s post), but for now, I am depending on electricity to pump water through the system.

Even if you don’t have an aquaponics system, this might come in handy if you have a pond that keeps clogging your pump or another water application where you’re pumping out of less-than-ideal sources.

What is Aquaponics?

Check out yesterday’s blog post, which describes this in a bit more detail. In short, aquaponics systems create a loop between fish and plants: fish excrete ammonia, which is converted to nitrites by beneficial bacteria, but these chemicals are dangerous to fish, so when more bacteria convert the nitrites to nitrates, it helps keep the fish healthy. As a benefit, those nitrates can be absorbed by plants. An aquaponics system pumps water from the fish tank into a grow bed, where the plants and bacteria clean the water, which then flows back into the fish tank.

Building a Low-Cost Pump Filter

Pushing over 4000 gallons through a pump each day (flow rate ~200 gal/hr) gunks up the pump without a filter. The filter also provides a surface for beneficial bacteria to grow. Instead of buying a filter system, I purchased a fountain pump ($30) and the materials to build a box filter:

  • Tupperware box with snapping lid ($3)
  • Scotch-brite-like scrubbing pads (4 for $2)
  • Scraps laying around my house, including plastic, nuts and bolts, tube for the water flow, bicycle tube cut into a strip.

First I created holes in the lid of the tupperware lid with a soldering iron (a great tool for cutting plastic, but use in well-ventilated area). First I did it on a 1/2″-x-1/2″ grid and then melted another set of holes between the first.

Melting holes in the lid.

Next, I created a holster to hold the scrubber pad. I cut it out larger than the pad and then cut out the inside. I used the soldering iron to make holes the same size as the small bolts through both the lid and the holster. Then I attached the holster with nuts.

Second set of holes melted and the holster attached.

Then I melted a hole in the lid just big enough for the outlet tube to fit with a bit of pressure and another slot on the side of the tub itself for the electrical cord to come out. I had to use a strip of bicycle tire to make a good gasket seal by wrapping it around the cord where it exited the tub.

Assembled tub.

If I had a flow problem, I could make a holster on the other side, but this seems to be enough flow for the water pump. And finally, a shot of the installed pump.

The pump working to push water through the aquaponics system.

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