New SLO design Video tour ~ Aquaponics Get Ready

Hi there

Long time no blog..

Today I put up another fishtank and built a pretty cool Solids-removal system for it.

The solids removal problem:

In aquaculture systems, solids need to be removed. Why? Well how you you like to swim in your own poop all day? Seriously, the fishpoop solids can start to rot and create ammonia and all sort of nasty things we dont want. Plus its nice to have a clean tank to show to visitors..

How is it normally done in AP systems?

In AquaPonics, there are two main methods to remove solids.

Pump-in-Fishtank (PIFT):

The pump is located on the bottom of the fishtank. The pump picks up the solids from the bottom of the tank, and typically the solids are dumped in the growbed, where earthworms will take care of it.. Problem is that the solids are picked up OK, but only around the pump. The opposite corner of the fishtank will remain poop-filled, and you will need to manually siphon it out, or maybe grab a net.

Solids-Lifting Overflow (SLO):

The fishtank has a pipe along its bottom with slits cut into it. The pipe elbows up the side of the tank and from there heads out to the sump. Sounds good, and works sort-of OK. Problem is that again, the bottom pipe does not reach everywhere, and again you have some poop sitting in a corner. A second problem is the size of the cuts in the SLO. If you make them big enough to always pass all the solids, then, if you have smallfry, you run a real risk of getting some smallfry sucked in. If you make the cuts small enough to keep smallfry from getting sucked in, then the cuts are likely to get clogged by poop and debris. Not good.

So what is my idea?

I noticed that in indoor aquariums, the Under-gravel filters work wonders in collecting fishpoop. In a typical aquarium, the poop sort-of collects under the filter plate until you eventually get around to cleaning it. These filters work by creating a negative pressure area under the filter plate (which itself is covered by gravel). Fishpoop gets sucked down through the gravel, through slits in the filter plate, into the cavity below the filter plate. The reason it works so well, is that the filter plate and gravel diffuses the negative pressure, so there is suction all over the bottom of the fishtank, as opposed to one or two areas, as in the typical AP setup. The other cool thing is that smallfry do not make a habit of swimming down deep into the gravel, So you have a system that can pick up all solids without any risk to the smallfry

My idea is to create an under-gravel filter that collects solids in the same way, but the solids are not collected and stored, but removed via SLO. We create a filter plate with a negative-pressure area under the plate (solids collection cavity), and have gravel above the plate. Solids are removed by a SLO mounted inside the collection cavity.