How big is the return pump? I would be concerned that it would shoot water straight up.
I don't know the specs of my pump off the top of my head. I figured I'd try and difuse it somehow. It may splash quite a bit, but I figure having the shell full of water would containg the splashes that a difuser would create.
Keep in mind I havent' implemented yet, but you bring up a good point. If you decide to try it, let me know and we can keep brainstorming.
Anyone else have suggestions?