Well there are always the hang on back skimmers. I think that everyone chooses sumps rather than. It is a good place to keep things out of sight... ie heaters, filter pads, skimmers, pumps, media, anything you can think of I bought mine with pre made baffles. Others like to build their own. I do like the DIY projects however I didnt have the time or the knowledge then to build my own sump. Also just getting a hang on back filter for a saltwater tank I do not recommend. My tank is a 75 as well that was pre-drilled for a reef setup. They are called Reef Ready tanks.. Most companies have them. I ordered my stand tank and sump and some other stuff off of Glasscages.com - Home
. You can customize your own tank on their site. You just have to go pick it up when they come near your town with their truck. Kind of weird but its worth it in my opinion.