Going to be closing my 15 x 30 above ground in a couple of weeks.
This is my second year of pool ownership.
I converted to BBB this year, thanks to the help from people here.
I've read that I need to bring the Cl up to 'shock level' then vacuum, etc.
What is the 'shock level'?
I used 15ppm for the conversion, would I also use it for closing?
One other thing, I have an Aquadoor for my skimmer, and if I plug my return jet, will I need to drain the water? I'm concerned about the frozen block of ice cracking my return jet or skimmer frame when it heaves or moves. (Is this even a legitmate concern?)
I'd really like to leave the water level high so I won't have as much to pump off of the cover in the spring.
This is my second year of pool ownership.
I converted to BBB this year, thanks to the help from people here.

I've read that I need to bring the Cl up to 'shock level' then vacuum, etc.
What is the 'shock level'?
I used 15ppm for the conversion, would I also use it for closing?
One other thing, I have an Aquadoor for my skimmer, and if I plug my return jet, will I need to drain the water? I'm concerned about the frozen block of ice cracking my return jet or skimmer frame when it heaves or moves. (Is this even a legitmate concern?)
I'd really like to leave the water level high so I won't have as much to pump off of the cover in the spring.