Are you going to put it under a stand? If so, what the biggest you can fit in there and still be able to maintain it. I would go with that. I'm currently building my own sump out of some salvaged glass. Maybe you can do the same with a customizable setup?
yeah, I am putting it underneath my stand, I have a 75, that I would really prefer not to dedicate to a sump right now, I had a 40g breeder, but I gave it to a friend, I told them they could have a tank for free(good friend, just broke up wants to get back into reptiles, or fish) and he picked the 40 over the 75, but anyways I will have to figure it out, I am trying to see if we have an acrylic fabricator int he area that will lemme get scraps.
My two issues with this is that, the stand is barely much wider than the tank which at the rim(widest part) is 19.5inchs and there aren't many totes I can get in there that would be significant size that I want without having to utilize two totes and plumbing them together with an equalization tube, which I do not want to do.
The plywood lets me put the exact dimensions that I want, and I am completely unable to get acrylic in the sizes that I want.