well in all my tanks that I have kept I have never done an overflow sumped tank, so, I set up a 180g with a 50g rubbermade sump. Initially I had about 15 fish that went over the overflow with some of them actually making to media basket and a few minnnows through to the sump. So I followed the advice posted on my thread and rigged up eggcrate as a way to keep fish out. I came back today and about 20 or so dead fish in the tank and sump. I did a 80% wc and will do another tomorrow moral of the story for me no fish under 7 inches in a big overflowed tank. I thought I could put my growouts in here but have come to see that big pumped overflows are only for big fish. I am amazed at what kind of fish can fit through egg crate when caught in the current.
So now since I can't put the growouts in any of my other tanks I added a 10inch aro, 10 inch tiger shovel, 2 knife 7 & 12 inch, so it should be about 2 days till all the little guys are gone at least their deaths won't go to messing up the water quality.