I have a 40g breeder tank that I am trying to make into a sump for my 75g reef tank. I am trying to make sure I get the best use out of it. I am currently planning on going with just a basic 3 chamber sump w/ a bubble trap, and am trying to get quotes from a few places for making the baffles. I was wondering what the best way to calculate the amount of space I will need for overflow water from my tank in the event of a power outage so that I can get the best estimate for the height of my baffles. Anyone able to give some advice?