Check Valve?

[Aquattro]

I think what I would do is come up over the back of the tank, down to the bottom and build a pvc manifold to discharge from the rock work. This gives you the effect you want and gives you the safety of a siphon break in the return. I just wouldn't be able to live with holes in the bottom of my tank that could allow for the tank to empty. And in my experience, when a check valve gets stuck, it will be when you're sleeping or not home. And it isn't IF, it's WHEN.