Total alkalinity high and pH drifting up...can someone explain?

I hope I'm being as clear about this as I can...so hear goes. This might be long. :o

Something is up with my TA...I think. Last Thursday, I got my water tested at the pool store, and I tested it myself with Wal-Mart Kit.

My #'s (Pool store #'s)
TC=3-5ppm (FC=4ppm)
pH=~7.8 (8.0)
TA=300ppm+ (120ppm)
Hardness=0ppm (185ppm) (i'm going to ask about this in another post:) )
CYA= less than 20ppm (0ppm)

So, that evening my husband added fill water, 4lbs of CYA, 1 trichlor puck, then 1/3-1/2 gallon of muriatic acid. Friday morning, TC was still 3-5ppm, pH was ~7.6, TA was 230ppm. (went swimming:D )

Saturday morning TC 3-5ppm, pH=~7.8. We were going away for the weekend, so I added 1 gal of 10% sodium hypo to bring TC up to ~12ppm and 2cups of acid.

Sunday evening, got home and tested. TC=5ppm+, pH ~7.6-7.8, TA 190 ppm. It also rained on Sunday. I added 2 cups of acid.

My questions are:
1. why does my pH keep drifting up?
2. Should I trust my TA numbers? I know it's "normal" to have a discrepancy in pool store vs. home kit readings. It is going down, which is good. But from what I've been reading, it's normall really hard to decrease.
3. Is tomorrow too soon to test for CYA?

Pool info: 12,000gal IG exposed-aggregate surface

I hope someone can clear this up!

Is it a new pool?
"Hard" pools (soft being vinyl or fiberglass) frequently push pH up when they are new. Owners add lots of acid during the first season.

But you Tot Alk (T/A) is WAY too high and you need to lower it to 80-125ppm--the normal range for a hard pool (vinyl can go up to 180 without a care). Go to the top of this forum on Alk and Calcium and read the stickied posts on lowering T/A. Baking soda and soda ash will raise your T/A, so don't let either near your water.

Calcium should be between 200 and 400ppm for your pool (for vinyl the allowable range is 0 to 500--that's why vinyl doesn't need calcium). You can use cal-hypo to chlorinate or just add calcium.

Wow, you're fast:)

No, pool is not new...We really don't know how old...house 14 years old, we've been here 2.5 years...

I just posted again in this forum about my Calcium level...

I've read the posts about lowering TA, and I need to keep pH low and aerate the water. We have a fountain and 4 returns into the pool, and we always keep the fountain on when the pump is on (it looks pretty:) ). So, could that be why my TA has been lowering and my pH drifting up? I've been lowering my TA without really trying to? And I could get it to go faster by keeping the pH lower?

I was just concerned about the huge discrepancy between my numbers and the pool store numbers...

It looks like your numbers are at least close to the pool store except for alk & hardness which are WAY off. I would be a little suspect of your numbers. Is your hardness really 0 ? In a exposed aggregrate surface that seems unlikely. I would tend to believe the pool store hardness reading of 185 then I would 0. Test your tap water is it 0 ?

And for the TA of 300 vs pool store of 120 I would double check my tests before putting a bunch of stuff in your pool to increase hardness and alk becuase if your numbers are wrong then it will be tough to correct. It seems in your subsequent tests your TA was really bouncing around radically. Is your test kit old ?

-- john

I posted in this section of the forum about my Calcium numbers. Turns out, there is interference with my reagent when my TC is higher. I added some more drops of indicator, and got 250ppm CH. Anyway...

My test kit is older. :o I think the reagents for TA and CH are older than the rest. I need to get a new test kit. My TA readings keep decreasing, while my pH keeps drifting up (even with constant additions of acid). I may go back into the pool store tomorrow and get the water tested again. I need to get my CYA tested because we added last week, but I"m out of reagent.

I just don't know which numbers to trust. Numbers are only as good as the tests used, and the people doing the testing. I trust myself, but not my test kit. The pool store...I'm not sure about either. At least the water looks clear and sparkly.