90+% isopropyl alcohol is used to unfreeze lines, and it also absorbs water. That's what is recommended by the aerator mfg's.
Unhook the line, pour a cup into the line, hook it back up.
Or get the freeze proof devices that Koenders sells. It automatically dumps iso into the line when pressure increases.
FYI if you can not find or have access to Isopropyl alcohol, wood alcohol will work as a substitute.
