Hello - just a heads up for anyone interested.
I added CYA to our pool last week using the "Sock Method" and dangled the sock in front of a return jet - I just laid the top of the sock on the coping and put a weight on it to keep it in place over the return.
I did this in two locations - one was on my stronger return - with the cover open - then I moved it to another jet when I closed our safety cover.
I had the top of the sock draped up over the coping, and the slight ribbing in the sock etched my coping a tiny amount. I now have visible stripes on the surface of my coping that match the ribs in the sock!
I did a little sanding to make it less obvious, but to get rid of it completely would require me to sand off the top layer of the very smooth concrete and start to expose more of the sand/aggregate.
It would have been better to hang the sock on a pole extended out over the water in retrospect...
I didn't see anywhere a mention of this anywhere, so I thought I would share my experience.