I have 2 canister filters and I was wondering...Im using one as a regular return from one filter above the water line to help oxygenate the water as it splashes down. Can I use the second return under water as a powerhead? Does that even make sense? I just figured if its underwater and pushes water around it does the same thing as a power head. Is anyone else doing this as is doesnt sound very hard. Would you recommend it?