A thought on the idea of dumping directly into the skimmer.

CYA is an acid. If you have sand or DE for a filter I don't see a problem, but if you have a cartridge filter I might be concerned about the filter, especially if there is a few pounds of it in the filter tank and the pump goes off for a while. The concentration might build up and do some damage. Depends on the cartridge filter material and I don't know what it is.

If you dump it into a skimmer sock, make sure the pump stays on and the kids or pets keep out of it until its gone.