Zeph... I found a link to this from the Barr Aquatic site. I have a question: Have you checked this in the event of a Power Outage?
It looks to me like the water would want to back siphon out of the upper raceway down to the level of the input at the far left leaving the tank nearly empty. You have a check valve installed? You could modify the input of the pump from the sump into the raceway to drop the water into the long tank or input the water at or very near the upper limit of the height of the water in the tank. This should keep the back siphon to a minimum.
Great idea though... I love it. Just wait til the wife goes out of town next
