I think that for a tank of that size, a sump is really up to you. If you want one, great if not, thats fine too. I have a 20g, and i dont have a sump. BUT, i do have a hang on skimmer (Bak Pak 2R, which i would rec. for a tank that size. Also, defenitely get some (a lot) of live rock and some live sand for a DSB. All three of those should pretty much do it for filtration, and also it wont take up as much space as a sump would. Also, defenitely upgrade your lighting. I hope this helps.