Aquaponics Swirl Filter


The Swirl Filter, also known as a solids filter, is commonly used in aquaculture facilities. It is also widely used in aquaponics systems to help remove fine particles produced by fish waste. This is particularly true in semi-commercial and commercial aquaponics systems in which hundreds of fish live.

The filter helps to maintain the clarity of the water in which fish thrive. Fish health deteriorates when food debris and fish excrement are suspended in the water. This is a necessity for DWC (Deep Water Culture) systems because debris clings to the roots of plants, which affects their growth and health.

In a system filled with media…

In a culture bed system filled with substrate, you would not normally need a Swirl Filter. The culture beds act as a Swirl Filter and capture debris in suspension. So, in a way, the more culture beds there are, the clearer the water is.

The density of your farmed fish, the species and the scale of your system are determining factors in whether or not to install a Swirl Filter. If you find that the water in your system is often so cloudy that you can barely see your fish, this is a good indication of the need to install a swirl filter.

I looked for the simplest way to build a Swirl Filter that is suitable for both a semi-commercial and commercial aquaponic system.

The general idea is to trap solid waste at the bottom of the Swirl Filter.

To do this, you must direct this pipe in such a way that the wastewater swirls and the waste settles at the bottom of the filter and cannot enter the culture bed.

Do-it-yourself instructions

  • Take a 200-litre barrel.
  • Drill 2 holes at opposite ends. One for the inlet pipe from the breeding tank and the other for the outlet pipe to the growing system (this must be higher than the inlet) as shown in the diagram. An adapter must be used to ensure the tightness of the pipe connections.
  • Get a laundry basket that fits into the barrel (a little smaller is good), then drill a hole so that the inlet pipe can pass through.
  • Take a porous material, filter foam or even an unused fabric. Tap it on the walls of the basket.
  • Now drill a hole at the bottom of the barrel to remove the solids. It can be a small PVC pipe with a valve to control the flow. This outlet allows you to empty the waste stored at the bottom of the filter.


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