DIY PVC UGF

I have two tanks now with this UGF in them and I'm really happy with the way they work. The two horizontally oriented legs in the center have two rows of 5/16" holes drilled in them, 90 degrees to each other, that are turned down toward the bottom of the tank. The other pipes are all solid.

You can't really see it well, but there's a piece of black plastic insect screen lying on top of the pipes. I use 4" of 1-3mm blasting grit as a substrate and add it starting in the center, molding the insect screen to the pipes and to the bottom of the tank. The insect screen keeps the substrate out of the pipes. If you cut the sheet of screen about as big as the tank bottom, it will scrunch up to about the right size since it only has to protect the perforated pipes in the center.

This tank is a 70 gallon and this is the only filter on it, driven by a small powerhead in the back left corner. I stuck the CO2 line into the venturi and can count bubbles if I really listen closely.

In these tanks I'm working under the concept that the plants get all they need from water column fertilizer dosing. (Thanks TBarr!) So the substrate is non-enriched and aside from the mechanical filtration it provides, is really just a glorified plant-holder.

Except: I used some used 1-3mm blasting grit for the substrate that had been previously supplemented with laterite. Other than placing it in a tub with water and scooping it out and letting it drain, I didn't try to get rid of every bit of the laterite. But most of it was gone. The only remaining material was small enough that it clouded the water for about two weeks, then suddenly clarified. So, there is 'some' laterite in there, but it's not much.

I overcoated the clear silicone with what they labelled as 'Black' on the back seals. It looks brown to me, but is still less intrusive.

TW