Aquaponics - Self cleaning swirl filter

Some stuff is better than other stuff.

This test is more like other stuff.

But it does illustrate the kind of thing a swirl filter might do if it were designed a bit better.

The first scene shows water entering through the thick black pipe on the bottom right of screen. The water exits the pipe via an elbow that directs water to the right so that a gentle whirl pool is set up.

You can see that the solids (these are real fish solids from a sieve I put under the inlet to the grow bed) do indeed collect in the centre and once they are there, they quickly sink to the bottom. Much of the stuff that looks like its going down into the standpipe (black centre) is actually an optical illusion. 95% of that is too low to be sucked in, but just appears distorted by the lensing that occurs with the water shape at the top of the tube. In the final product, a bell would sit over the top, so that wouldn't be happening, but that's the exit pipe back to the grow bed, so that's where we want the solids to go anyway.

After the bell siphon magically appears (I must learn how to do better scene transitions), we see the siphon kick in and most of the solids get sucked in, to return to the grow bed.

I add the same solids back again after collecting them with a spoon from a sieve.

The clear plastic tube on the left is where clean water would be drawn off to feed the NFT tubes. Water only exits via that tube for a few seconds at the top of each cycle. The length of time that water flows can be varied by the flow rate allowed through the tube. If you have a flow rate that takes a lot of water, it takes longer for the siphon to kick in. The exit flow could also be adjusted by simply moving the tube down a little from the rim. I placed it high because my little bucket was never going to be deep enough, so I was trying to get the most out of what little depth I had.

All in all, I guess this test was a success, even though it didn't work as well as I would have liked.

I Think it works well enough for me to have a go at making a bigger, better one.


  1. The only drawback I can see to using a Bell siphon is that the system dumps every cycle. Accumulation of solids is minimal and a large quantity of water is used each time. Plus side: it is 'maintenance free'

    A swivel siphon allows you to accumulate larger quantities of solids and uses less water when flushing. Drawback: it is a manual operation.

    1. I think I have a plan for that by using a deer scarer connected to the top up water. I'll explain more in a future post.


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