Hi all- I have a question about balancing the chemistry of my pool before closing. This is the first summer I've owned the pool and the chemistry has been pretty stable up to 2 weeks ago, but the PH stayed at the lower end. I was primarily checking the FC, CYA and PH weekly with an occasional check of everything. Went on vacation 2 weeks ago; while gone it rained quite a bit and chlorine tabs ran out, so came back and tested yesterday- FC at 2.5, PH at 7.2 and CYA at 90. Some green spots in the pool from leaf debris, but not much. I got in yesterday (65 degrees) and brushed the pool, removed all the leaves and vacuumed. I used a calculator based on the CYA to get the FC up to shock level and added 4-121 oz jugs of 6% bleach per the calculations. Kept the pump on rest of yesterday and overnight and today checked all the chemistries (except the combined chlorine) and found this:
FC: 38 (was supposed to be at 36ppm for CYA at 90 per chart)
PH: greater than 8 (quite a jump in one day- not sure why)
Total Alk: Never did turn red- turned from green to clear and stayed clear forever and I stopped adding drops after 140 drops. I used 25ml pool water to calculate and on hindsight should have done the 10ml and used those calculations.
Calcium hardness: 200
I just realized that I haven't been checking combined chlorine at all- so not sure if that was needed along with everything else.
I'm assuming I'll need to fix the Total Alk and PH before closing the pool, but I'm wondering if my adding algaecide before closing will affect either of those readings?
Secondly- I know that to balance my CYA I'll need to drain the pool and refill, which doesn't quite make sense to do before closing - drain 1/2, refill, then drain to 6" below skimmer. Will it hurt to leave the CYA alone and just refill in spring?
Thanks ahead of time for anyone's help