salinity

Hi Guys, Ive kept freshwater and marine tanks before, going to try my hand at a brackish one now. In your experience, what is the minimum salinity in which a protein skimmer becomes effective? Thanks.

As the title implies, i currently have a low tech planted community 135gallon that i want to turn into brackish. I am bored to death of the community tank... time for something else. My original thought was discus, but then i got side tracked on pictus cats and african cichlids, then angels...