So I recently switched from dosing to a calcium reactor, and back when i was dosing I was getting a lot of precipitate clinging in thin sheets to my sump and unknowingly... my skimmer inside the body! I was looking at it this weekend and notice that even though it still seemed to be skimming fine I noticed that I didn't seem to have as many bubbles in the body of the skimmer. I could actually see the pvc pipe inside the body which is normally obscured by bubbles. So first I ran just the pump in a vinegar bath, but that didn't seem to do anything. Then I checked the whole venturi area and that seemed pretty clean. That's when I had noticed all the build up inside the skimmer. So i broke it all down and started hosing out the body. I had sheets of calcium carbonate or whatever it was falling out in big flakes. After getting all of that out of there, I put it all back together and ran it in a vinegar bath for around 4 hours. After that I opened it all back up and wiped it all down, all squeaky clean. Once that was done I put it all back in my sump and started it up. BAM! The body was completely thick, milky white... completely opaque with bubbles. This was like 10pm at night. By the next morning I had a half inch of nog in the 8" cup. Might have had more but I had accidentally left the drain valve open. Oops.
Here's the "after" pics...