sump

[Troy F]

A sump and skimmer won't mess with your water chemistry at all. The sump will make your life easier as it's a good place to do any chemical filtration as needed, a place for your heaters and skimmer, you can have some live rock in there for additional biological filtration and a refugium and the extra water volume will be nothing but an advantage. I've run both a tank with a sump and without and hands down, the sump is the way to go.

As for the skimmer; I wouldn't run a tank without one.. That's not saying you can't, many have done so successfully. If you're willing to do frequent water changes and have some other export mechanism in place, you'll do fine I guess. If you don't and also don't run a skimmer, eventually you'll run into nutrient problems.