I have a built in reef type tank and it works great. A sump is a good idea no matter what if its a reef you probably would not need the bio balls. Your sure about the acrylic you may be sorry. You may or may not know how much you have to clean the glass on a mature tank. You will scratch the crap out of it eventually. Bump it with live rock theres a scratch, catch a little sand in your glass cleaner theres a scratch, they also can warp.