I bought the black air line tubing and it works. My concern is this "white" build up that seems to only affect the tubing. I don't see it anywhere else inside my tank. It comes off easily when I'm cleaning but, builds back up quickly. I'm thinking mineral/calcium deposits like you find on the rim of the tank after a while? I do get that kind of build up on the rubber gray connectors on on my canister intake/output hoses. Insights always appreciated.