I started with a 75 and it was just a plain tank. No overflows or drill holes. Started with just a hang on back filter. Worked great. Then I took that off because I wanted to upgrade to a sump so I put on a hang on back overflow and that worked just fine. I think the overflow would take up too much room in a 75. I have seen them with overflows and its not much room they take up, but for me, I always want as much room in there as possible. I never had enough room in the 75. Had to upgrade to a 220.