How much baking soda?

[thewayne]

My pool is a 20,000 gal AG vinyl liner.

last night I tested with my HTH 6 way and got these numbers.

TC 0.5
Ph 7.2
TA 120
TH 500
CYA >100

I took some water in to the pool store for testing today and they got the following numbers.

CYA 100
TC 1.5
FC 0.4
Ph 7.1
TA 86
Adj TA 56
TH 220

[waterbear]

Wtih your stabilizer that high the adjusted TA might be a more valid reading. CYA will test as part of the TA. When the CYA is in normal ranges it can pretty much be ignored but when it is as high as yours it shows as a large chunk of your TA. My advice would be to do a partial drain and refill and get your CYA down to about 30-50 ppm and then rebalance the water.

[duraleigh]

Off the subject, but, regardless of who's numbers you trust, chlorine should be your priority right now...not Alk.

If the pool store tested correctly, you need to shock your pool. I would move Cl up to 25-28ppm in a vinyl pool and 30+ if it's concrete.

Then let it drift down into the 5-10ppm range and keep it there until you decide what to do about the high CYA.