Yesterday I added enough CYA to raise my level from 30 to 40. It was a granular form that I purchased at Lowes. I tried to dissolve it in a bucket of water but soon learned it would not dissolve. Then I remembered reading something on here about putting it in a sock in front of the skimmer so I did that. I added 22 oz by volume and after it had been in the water for a few hours I checked on it to see how much had dissolved. By squeezing the sock, I could see the white liquid flowing into the skimmer. It didn't take long to get all 22 oz disolved.
My question is, since it went through the sand filter first is that why I should wait about a week before retesting the CYA level? Does it take that long to work it's way through the sand in the filter and get into the pool? Would it be better to hang the sock in front of my return as I have now seen suggested on here?
Last night we got a lot of rain and more coming this week. I will need to drain a few inches water from the pool in a day or two most likely but don't want to lose any of the CYA by pumping to waste. Would it be better to use a hose and syphon the water out of the pool instead of using the pump? My filter pressure is still low so I won't need to backwash for a while.