Will this adjustment to CHOP2 system work?

[Amy Lu]

I am Amy, a beginner from CA. I am currently designing my first AP system. I have an idea of making some changes on the CHOP2 system, but not sure whether it will work. As in CHOP2 system, water will be pumped out from sump tank to grow bed, through the auto-siphon water from grow bed will run into fish tank directly instead of running into the sump tank. The water in the fish tank will overflow into the sump tank through gravity. I think in this way all water from fish tank will get filtered through the grow bed. I worry that I may missed something important. Any suggestions and critics are helpful! Thanks!

[Chris Cates]

It will work.  You just need to have your fish tank lower than your grow beds, and your sump tank lower than the drain in your fish tank.

[Jeffrey Ihara]

I had considered something like this when I was deciding on a plan, but Chris' point--that the grow beds would have to be quite elevated--became a problem. For me, trying to support 1000 lb+ of gravel four feet off the ground didn't strike me as being the best idea in earthquakeland USA. If you have a structure that will work for this or if you can dig a hole for your sump or if your growbed is small enough or light enough, then maybe.

If you haven't already done so, I'd suggest looking at some of the solids lifting overflow (SLO) designs for the outflow from your fish tank. Some work better than others (mine isn't so great).

[Chris Cates]

The grow beds don't actually have to be that high if you bury your fish tank.  The sump doesn't have to be lower than the tank, it just has to be lower than the hole in the side of the fish tank for your drain line.  If you're using an ibc and you bury the bottom 3 feet of it and have your sump buried a few inches lower you'll still get the drainage from the fish tank and your grow beds only need to be enough higher than 1 foot to drain properly into the fish tank. 

I don't know how the fish will react to the drains dumping into the fish tank if you're using siphons, it might disrupt feeding, but it would aerate the water well. 

[Amy Lu]

Hi Chris, thank you very much for your comments and suggestions. I plan to use inflatable swimming pool as fish tank and the sump tank. Apparently the fish tank will be slightly higher than the sump tank. Have the water come out of grow bed through siphon outlet, can I collect some pipes into siphon outlet and extended into the fish tank? I thought in this way I can avoid all the splash and make it quiet. Is that practical or it will be too hard to the siphon to work with all the extended pipes? Another idea is setting up a raft system on the top of sump tank. Is that practical? Looking forward to hear your opinions. Thanks!


Chris Cates said:

The grow beds don't actually have to be that high if you bury your fish tank.  The sump doesn't have to be lower than the tank, it just has to be lower than the hole in the side of the fish tank for your drain line.  If you're using an ibc and you bury the bottom 3 feet of it and have your sump buried a few inches lower you'll still get the drainage from the fish tank and your grow beds only need to be enough higher than 1 foot to drain properly into the fish tank. 

I don't know how the fish will react to the drains dumping into the fish tank if you're using siphons, it might disrupt feeding, but it would aerate the water well. 

[Chris Cates]

I'm not sure about inflatable tanks.  Can you cut a hole in the side for a drain?  Somehow I don't think that will hold up.

I was suggesting you mostly bury the fish tank and bury the sump even more to get your gravity flows right.  The top of the sump has to be lower than the opening in your fish tank for the drain, and the fish tank has to be lower than the drains on your siphons.  If you can't bury the sump and fish tank then I'd suggest you stay with the standard chop2 layout. 

You can float rafts on top of your sump and fish tank if you want as long as whatever fish you're using won't eat the roots.

I've been telling you this is possible, but I don't really think jumping through all these hoops to change the flow is worth doing.  I have a standard chop2 system and it works fine, although I use a separate pump to feed the fish tank. The water quality in the fish tank is excellent as long as we don't leave our air and fish tank circulation pumps unplugged over night.

And my system isn't any louder than a garden water feature even if all the siphons synchronize and dump at once.