The small storage of water inside the carbon skimmer is heated/cooled to match the temperature of the machine (or its surroundings, according to some).
When I noticed something strange happening the storage of the skimmer was rapidly oscillating between something near the input water temperature and building/area temp about 15 degrees higher.
I attempted to reproduce the issue that I am trying to report. Attached is my simple test rig. I am NOT able to reproduce this. Replace the oxygen in skimmer box with co2 to start and bring back oxygen to stop the thing,
The original map I was playing is also not repeating the behaviour I am trying to report.
If I ever see this again there will be screenshots.
Not known, sorry.