Nope. freshwater lacks the proper specific gravity for foam fractionation (skimming) to work effectively.
And with an empty tank, you won't have any DOC
's to skim out.
As far as hooking it up and running it, yes it'll run in freshwater and won't be damaged...it just simply won't skim anything out of the water. And skimmers have to run for about a week before they start skimming in a consistent fashion anyways.