I am not sure what you mean?? The overflow and return works like they are intended.
On a separate note, I did some experiments with the controller from the wave box last night. A regular Tunze 6100 pump with this controller can produce 2 inch waves, WITHOUT the box:shocked:.
It looks as if at "low tide" the water is below the overflow. Will there be a surging effect happening in the sump? I'm guessing that the returns have to be submerged below the "low tide" point? Also is there anyway that while at the low point, too much water will be pumped into the display and cause an overflow when the box hits it's "high tide"?
This tank is not plumbed right now, I am just water testing. I do have a wavebox on my 150 Gallon(48Lx30Wx24T) reef, it has two overflows in the corner, kinda like this tank. The water level within the overflows does surge slightly with each wave, the two drains are connected thru a manifold before exiting into my UV, skimmer, PO4 reactor and carbon reactor. From what I can see, the surges from the two overflow cancels each other out when the water is mixed in my drain manifold.