The two returns in back are going to be down in the rock work, and the one on the far rear left and right will also be jetting through the rockwork to a good extent. I also intend to have the entire rockwork suspended on pvc
racks for two reasons... I like having caves, and I like having the free flow through of water from below. Keeps the detritus factor down. That was/is my biggest problem in my 58, not enough flow through. I had toyed with the idea of a drilled rockrack with a steady flow of water in it, but it got too hard to plumb. I think the oceansmotions will do the trick.