Hillsy has build a great little system using IBC’s and bathtubs. The system is based on the Chift Pist principle, with an IBC sump tank that’s part buried in the ground, a fish tank next to it, and three bathtubs on the other side laid out in a U shape.
Little things can often make a system and Hillsy has spent quite a bit of time and effort in making his system not only perform well but also look good. One of the really nice features is the small viewing window in the front of the IBC. Also the partially sunken sump tank has been lined with timber for extra support as well as a nice added look.
The system uses a 6000L/hour pump to pump from the sump tank up into the fish tank. Hillsy has installed a 90mm solids lift over flow coming up from the base of the IBC and out the side of the IBC through a nice flanged fitting that has been silicone and bolted solidly with stainless steel bolts.
Just before the growbed his irrigation line has been reduced from 90mm down to 40mm, with three individual outlets going to the three bathtub growbeds.
Hillsy has installed auto-siphons in each of his bathtub growbeds, with standard 40mm DWV piping and fittings flowing back to the sump tank from the beds. Hillsy did find that using DWV pipe and fittings wasn’t quite as easy as using standard pressure pipe and fittings. Firstly, the pipe diameters are a fair bit smaller, and generally you want to keep your drains as large as possible. Secondly DWV elbows are not 90 degrees, but they’re about 85 degrees making plumbing a little more complicated.
Over all a nice simple system that works well and looks good while making use of recycled materials. Hillsy has made some modifications to the system over time including adding a number of different swirl filters, canister filters and biofilters to the system. He has also been experimenting with adding a venturi on the return line going into the fish tank, this is a fantastic, efficient way of adding extra oxygen into the fish tank.