When I ran this setup, I would get excess moisture at the bottom of the media canister. It wasn't foam from the skimmer, just a collection of moisture from high humidity. That moisture would bubble somewhat if it was high enough to touch the media, but it was minimal... If your reactor is actually pulling foam from the skimmer then that might be an issue.
You're mostly right. It also contains ethyl violet for the color change indicator. I would guess that is something you don't want to get into your tank.
I think you are right with too much moisture, so is there anyway to fix it, i once seen the water pull through the media and i don’t want that to happen so right now i just run my scrabber to pull the air from the room.