Real simple, and just a prototype. 1x1" aluminum angle stock small sheet of 1/6" aluminum and 2x4 which will be drilled out for the jet/ PVC pipe. The water shoots into the folded down piece that was cut and forces the water down and also acts as the feed. I used rivets to hold it all together. There won't be any holes drilled into the PVC to wash the gravels just the pipe. I think it creates back pressure on the pump and wears down the battery faster that's why I have the flap to keep the water down