I have an acrylic tank that has an overflow area on each end. The tank has a top on it that is seamed in place. There is a 1/4" gap between the top of the overflow wall and the ceiling of the tank AND there are 42 - 1/4" x 1" cutouts along the top of each overflow wall. So, the question is, how do I calculate the amount of water that can flow through these spaces and into the overflow areas in a given period of time? Surely there is a magic formula somewhere that will help with this calculation! I have attached a drawing of one overflow as a pdf. There is one at each end of the tank. Also, I assume that the fact that this is salt water will make a difference to the flow rate and thus the volume per hour. Why, you ask, do I need to know this? Because I am designing a closed loop circulation system on this tank and don't want to push more water through the circulation system than can actually fit. There are cut outs in the top which would allow salt water to flow into my basement and run the tank dry if I goof this up. Thanks for your help with this. i know corals and fish, but am short on fluid dynamics!