Thanks for the help guys, I think a 20 gallon would be sufficient. I want to have a bio ball section where the water enters the sump, a protein skimmer section, and of course the return pump. I do not think I would do macro algae since I'll be gone to college again in a few months, and it would just be something else for my parents to take care of. I'll be using an overflow box since my tank is not drilled.
40 gallon FOWLR
-2 ocellaris clowns (mated pair)
-1 diadem pseudochromis
-1 flame hawkfish