I don't know if this will help, but this is my little "standard" go to sump design.. 3 chamber, and the thing about it, it's that is highly flexible from a 24 to 60 inch tank(box). The balls height, I pretty much choose to be on the safe side of power failure, while at the same time, if I run out of water in my ato boxing a good 24 hours before I run into any possibility of the pump running dry..
The picture(with the heights) is on a 30 long tank, but, I have in, as you can see in the running sump, incorporated that into a 75 gallon tank also.. The 75 holds 30 gallons of water, though it doesn't seem like it. The skimmer chamber holds 15,the fuge chamber holds 10, and the return section holds 5 gallons(even though it seems tiny looking at the picture ). My goal and next project one day is to go up to a 5 foot sump. Then, then only thing I will increase is the skimmer/filter sock section, as my skimmer now is 10" in diameter(11x10. 75 footprint), so it makes it a tiny bit tight..
Hope this helps even a tiny bit..
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