overflow boxes and ratings

[johns]

I have been having trouble contacting Oceanic for this info: Does anyone know what the overflow rating is in gallons per hour for the Oceanic 75G Reef Ready tank? If you get 2 overflows, does that simple double the rating?

Actually I have been toying with the idea of getting the tank drilled and factory installed with a second overflow box in the other corner. What do people thnk of that idea? I figure that maybe I could get enough circulation and avoid additional powerheads this way. It would also act as a back-up in case one of the drains fails (so the sump wont flood the tank). Is there a downside to doing this? And how do I choose a return pump if I do this - double the normal rating I would need?

thanks again
john

 

[reefland]

600 GPH is typically the given rate for a 1 inch bulkhead. If you have two then yes, that should double. However, like everything the real answer "depends". It depends on the teeth spacing which limits the amount of water that can enter the overflow chamber. It depends on the plumbing job you do -- add a few elbows and you create enough back pressure in the drain lines to reduce the max flow you can handle.

I've been able to push my bulkheads way past 600 GPH but I wouldn't recommend it.