Turning my 90 Gallon, into a Peninsula?

[SteveMM62Reef]

I have a 90 Gallon All-Glass, that has a bad seam behind the overflow. Also I was talked into cutting the Overflow to get the flow up, a huge mistake. Someone suggested I cut the Overflow completely out. Repair the seam. Drill two additional holes in the tank, and put a straight Bulkhead across the end of the tank. On a setup like this, I wouldn’t want any wave pumps in the tank. Is there a dependable option for a variable flow off of twin, or quad returns? BTW I have a Squid, but it turned out to be the pump killer.

 

[Timfish]

I'd use two return pumps with a controller to switch them. I'd imagine there are remote controlled valves that would work but I don't have any experience with what would work well with your application. I'd be hesitant to use valves for sprinkler systems unless they are rated to work with caustic fluids.