What are your plans for your tank? Fish Only (FO
), Fish Only with Live Rock (FOWLR
) or reef tank?
Unless you plan on going to a full reef tank there is no need for a protein skimmer. Even with a reef tank many people don't use one and have no problem without it.
Partial water changes (15% - 20% weekly) can do wonders to eliminate DOCs (dissolved organic compounds).
I'm assuming the tank is not predrilled to allow you to have a sump under the cabinet. You can get a overflow box that will hang on the back and move water from the tank to a small tank (sump) under the cabinet. You can place heaters, etc in the sump so they don't take up tank space and look unsightly. You can also then place a PS in the sump.
Everything You Always Wanted to Know About Sumps, Part I