Aquaponics - Solids removal

I'm actually a firm subscriber to the idea of leaving all solids in your aquaponics system, but I don't really have anything to inform that decision other than my thinking it. 

So we cant have that.

A healthy system can absorb a lot of fish waste and solids break down in no time. There are worms to help with that in the growbeds, but even without worms, friendly bacteria are always there to do their thing.

There's also the point that removing solids is removing hard earned nutrient from your system that the plants need.

There's also the fact that as my system stands now, I have a nice feeling that I'm working comfortably within natures guidelines and margins for error.

But enough of the sensible reasons for not messing about with solids removal. I'm going to have a go at it.

There are a few experiments from my recent past that I can call on. One is the swirl filter and it's followup, the self cleaning swirl filter. The self cleaning swirl filter was designed to separate solids, but keep them in the system, and I encourage you to click on the "self cleaning" link if you feel you might enjoy watching a video of fish poo swirling and settling. The reason I made it was to gain a source of clean water for my NFT (Nutrient film technique) pipes, but it might prove useful in this current endeavour.

I might also need a bit of electronics.

And an invention engine.

And a bit of a mental shift. I think I need to focus on water removal or recovery rather than solids removal. I need to get the water solids mix dryer and dryer.

Currently my plan looks a bit like this...

Step 1. Split the solids from the majority of the water flow using one of my self cleaning swirl filters. I suspect I'll be able to take out 90% of the water at this stage. It look like I might be able to do this stem more than once to get even more water out.

Step 2. Further separate the solids using gentle flow of the remaining water over or through a mechanical filter. Apparently, this will take the form of a conveyor belt sieve that slowly or perhaps intermittently eases solids from a water bath. At least that's what the invention engine seems to think. 

Step 3. Automatically convey the solids to a worm farm so I can add household veggie scraps and create high protein fish food. By returning the fish waste as fish food, I can still keep a natural eco-loop going, and continue to feel good about my system. Also, the fish really like the worms, and in winter when silver perch go off their pellet feed, it might be a good way to keep them growing.

Two things the final design will need to accomplish are that it will need to be very reliable, and that it will need to be very automated. I'll need to be able to go away for a week and ignore the system, and I'll need to create some failsafe system to make sure that I dont end up overloading the growbeds.

There is a great danger of overloading the system, because in order to have enough nutrient for the plants, I'm going to have to overstock my system with fish if I'm going to remove most of the solid waste.

120 Things in 20 years sees me cautiously optimistic about an automatic, aquaponics, solids removing, worm farm addition to my system.


  1. I am with you in keeping the solids in the system. I just don't want them in my aquarium, as it's kinda a display thing and should look tolerably OK.

    So I made a solids lifting overflow box. It can pull the solids off of the bottom of the aquarium and move them into the sump, where I don't care if they hang out for a while.

    Except that a lot of the solids stay in the overflow box. When I moved the box after about a year and a half of use, it had about an inch and a half of crud in it. About half of that was aquarium rock (HUH???).

  2. Thank you for sharing. Nutrient removal and recovery solves two problems by reducing nutrient contamination and recovering nutrients for reuse as a fertilizer.


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