I used a vinigar solution, as I had the same thing. I bought a 75gallon with
20 gallon sump, and everything had gak from the reef that used to inhabit
it. A soak in the vinigar solution loosened up the worst, I scraped off some
more while it was wet, and the rest that wasn't visible to the casual
observer I just left.

Good, a vinegar soak it is then. This doesn't have to be squeaky
clean, as I'm sure it won't take long to develop it's own coat of
freshwater goodies. But I did want to start clean, without the
sal****er stuff.
thanks-

James