How much brown algae is to much?

[Studawg]

It is okay to add the clean up crew already? I have a 90 gallon with about a 10 gallon sump, a rubbermaid for now. Yes i am running a skimmer and it seems to be working, the browny gross sludge in the collection cup is a good indicator i take it. As for substrate I have an inch and a half give or take some in parts. i plan to add more liverock in a week or so, should i wait on the invertabrates?