First, let me say - this website has been a great source of information to us this summer and our pool has been the better for it. Thank you!
Second, let me admit that I am NOT a pool expert and am still learning MUCH about pool chemistry. We did many things differently this summer based on your Pool School; however, we were not able to follow all your recommendations (such as emptying 40% of our volume to adjust CYA). My husband stood firm on that. So, we used A LOT of bleach and back-washed the filter frequently!
Third, we ARE following your guidelines for pool closing, including draining our pool to within 4" below the returns. Trust me when I say this is a HUGE step for my husband (who was advised NOT to EVER drain the pool on account that the sides would collapse due to ground pressure). After reading many posts here from those with similarly constructed pools in similar climates, as well as research on other websites - my hubby is willing to try it this year. Thus, that should help our CYA for next season.

Here are my questions:
Yesterday, I shocked the pool and used more chlorine than the PoolCalculator recommended (because it's taken more than what the calculator recommended to get to the proper levels all season). So, I added an extra jug choosing to err on the side of "high" rather than "low."
I also checked pH and TA - they were just a bit higher than what was recommended (7.8 and 230, respectively). I could/should have left them alone, but I chose to add Sodium Bisulfate to try to drop the pH a little to get it "just right" at 7.6. I added approximately 24oz per the dosage guidelines listed on the bottle.

4hrs after adding chemicals, my test results (partial) were:
FC: 25
pH: 8.2 (WHAT??)
T/A: 270 (?!?)

Here are my test results as of today (24hrs later)
FC: 23
CC: 0
TC: 23
pH: 8.2 (Grrrr)
T/A: 210 (Hmmm)
CH: 340
CYA: 40
Temp: 58

Soooo...what to do now? How to drop that pH? I added acid yesterday and the pH went UP! Why???
Can/should we still close tomorrow? What are the concerns w/ that pH being so high? What a mess.
Thanks in advance,
Molly

What was your FC level when you originally checked your ph? FC levels above 10 ppm can cause the pH to read high, so you really need FC below 10 ppm to know what your ph level is.

By the way your CYA level of 40 ppm should be fine (don't know why you want to lower?).

With FC that high, PH is going to read higher than actual, as Linen already pointed out. But the TA test results should be correct regardless of the FC level. With fairly high TA levels you are going to want to lower the PH to somewhere around 7.2. But you can't do that until the FC level falls enough to allow the PH test to work again. Since you are in a mild hurry, I would try the PH test as soon as FC is 15 or lower. It will still be off a little, but it won't be wildly off the way it tends to be when FC is in the 20s.

Unfortunately, I do not have FC levels from before shocking the pool in preparation for closing.
I have partial test results from that morning:
TC: 3
pH: 7.8
T/A: 230
Temp: 56

I don't have FC results from before shocking the pool because my TF-100 kit didn't arrive until that afternoon. I tested for FC after adding 6% bleach (6 jugs of 182oz) to achieve shock levels.

Thank you for the info about the pH not reading correctly at high FC levels, that's good to know!
What are the recommendations for lowering my T/A since I cannot accurately lower the pH to 7.2 before aerating? (I don't even know HOW to aerate, to be honest).

If I have to wait for FC to get to 15 - we won't be closing tomorrow. I've a feeling it will take forever for the level to drop from 24! My husband is NOT gonna be happy about that - totally my fault.

CYA does look good now. It was high at the beginning of the season - around 80-90, if I remember correctly. Pool Calculator said to drain 30%-40% of the water off. I was anticipating that draining the pool for closing would help remedy our situation for next season. So, I was rather surprised to find the CYA at 40 when I tested it today (not sure how it dropped over the summer except through water evap and rain refill?).

Well, it seems there is no ideal answer. I suggest calculating the amount of acid required to lower PH to 7.2 based on some assumptions (call the PH 7.9 and TA 210) and then add about half as much acid as calculated (so PH doesn't accidentally go down too low). The odds are that that will work out fairly well. However, to be really confident, you will need to wait until the FC level comes down.

Thank you!

We will try that - we're off to Lowe's to look for muriatic acid.

I did find the posts that showed home-made "fountains" or aeration devices, so we will pick up some PVC while we're there and have that on-hand in case the pH drops too low.

The good news is that FC dropped significantly since yesterday (shocker for me) and I was very pleased to see it register at 16 today. Woohoo!

So, we will add the acid this afternoon and re-test after a few hours to see where T/A lands. Then, we will re-test all the pertinent levels tomorrow hoping that FC has made another significant drop. One thing working in our favor is that the past 3-4 days have been sunny with this bit of "Indian summer" we've been having (air temps in the mid-80's).

We will shoot for closing either tomorrow or Monday evening. Not a bad deal.

Thanks so much for your advice. Sorry to be a bother!