Our system is healthy and the pH, ammonia etc. are all good, but between the roots and solids in it, our grow bed is very slow to drain and is at the point that the surface is 50% flooded (unless we turn off the pump to stop cycling) and starting to leak over the top of one corner...We have a 200 gallon IBC setup w/ ~100 tilapia with 1 IBC grow bed (I'm sure we need more beds but don't have the space at the moment.) We also have worms and the plants love them but they're pooping up a storm. We're trying to get a solids filter installed but as I'm sure you all know, there's a lot of tweaking that happens with these things :) The obvious solution seems to be cleaning out the bed-which I have pulled out a lot of hydroton, roots and plants already with little effect. So, short of pulling everything out and essentially starting over, is there a better way of flushing the system? And/or something else that we're missing that's causing the backup?
If you don't already have a working overflow drain, I would suggest that you install one, out the side of the IBC grow bed, above the level of your syphon, and plumbed to return excess water to the fish tank. The overall drainage though, will probably get worse and might require a bigger and bigger overflow until the solids filtration improves.
I hope this helps.
I have thought about this and never tried it but what if you forced water in reverse back through the siphon in rapid succession, kind of like a plunger for your toilet. Do it enough times and I would think you would make some space to the water to drain where it is currently constricted. Would it clog again over time, probably.
What type of siphon do you have?
Also you could probably harvest about 90 of those fish and you would not have this problem.
Like Jonathan said, that sounds like way too many fish for a media-based home system of that size. One general rule of thumb to go by is 1-2 fish for every 10 gallons of water. You can read more about stocking densities at:
Thanks for your replies. We ended up just diving into a "flushing" operation that afternoon...Basically we bypassed the drain so we could flush water with a garden hose through the grow bed and drain it outside the fish tank. Lots of work churning up, flushing and even taking hydroton out to clean it; did this to most of the bed (although we still had a lot of plants and living roots in there that we didn't move). We also have discovered that the grow bed itself had settled rather unevenly on top of the fish tank causing the water to pool in one corner so we put some shims underneath to level it out. This in turn actually corrected our swirl filter issue so we could start using it....and boy is it doing an amazing job! Holding our breath as we left town 2 days later, we came back after a week and the filter is completely full of gunk from doing its job, fish water is clear and the plants and some new seeds that I threw in are thriving! As for the fish, we thought we were on track with 100 in 200+ gallons; must have been led astray somewhere in that research. They aren't big enough to harvest yet so I think we're stuck for a little bit. We do have some plans to expand the setup, install a sump tank and another IBC waiting to go... Thank you for your suggestions and support! Loving my garden again :)