My AIO is 6’ long with overflows on each end. Currently one side has a filter sock + the draw for a HOB refugium (I added it some time after writing this original post).
I could put one on the other side’s filter sock holder but I believe as flow was restricted it would just increase flow on the other side, so the filter sock would never trigger and roll new media. Purely speculation.
So in my mind I could see 2 working in tandem and while they may not roll evenly, as one become more clogged it would push water to the other one until it became more clogged and they would kind of alternate. With just one I’d end up with one overflow doing double duty.
I might be able to get away with one and close off one overflow but that’s a recipe for disaster and my “sump” is high flow so I’d have to dial back my return.
if I ever do try it, I’ll let you know.
