Newbie here! I just took over chem service from a weekly guy (bought the house/pool a few months back).
In short, I'm trying to shock but the CYA is staying low & I don't have any separate stabilizer at the moment.
More detail: I don't think I'd been adding enough chlorine, so had mild algae growth recently. My CC was at 1 yesterday so I decided to shock. I lowered the PH to 7.3 this morning in preparation. I have 6 jugs of 8.25% ready. My CYA was <30ppm (which is weird because it was a little high just a few weeks back, 70, when we had someone taking care of it for us...but it's been raining a lot since so I assume the 12 in of evacuated water during the time lowered it?). I know it's a no-no per most of TFP advice but I had a box of AquaChem ShockPlus packets from the previous owner & I hate to waste so decided to use it since it said PH neutral & we actually needed CYA. Packets say 1 per 6k gallons so I added 2 & 1/2 jug of bleach (not too far off what PoolMath recommended to get FC to 12). Measured 2 hours later & have FC up to 6 but the CYA is still less than 30. These packets could be pretty old for all I know... does CYA break down over time/exposure? Does it take longer to 'show up' in tests (i.e. should I wait another couple hours & test again), etc.? Any reason I shouldn't add another packet or two to get it up to the desired CYA & corresponding shock FC (12-16 probably)? I also have pucks but assumed the CYA release would take too long on that front.
Thanks in advance!