Chlorine Just Disappears After Shock

[JohnnyB]

This spring at pool start up my attempts to shock and add 2 gal of 12% liquid chlorine to my 12k gallon vinyl pool have failed. Good news is the water is clear, for now. Using my Taylor K-2006 test kit here are my numbers:
FC = 1.0
CC = 1.0
PH = 7.2
Alkalinity = 220
CH = 310
CA = 100

[PoolDoc]

Sounds like you've had partial degradation of your CYA into ammonia. You can't easily drain, but it may be best to do a partial drain and refill. But, you do NOT want the pool to turn into a slime-pit while you decide what to do. So, do this:

1. Do a dilution test on your pool water, using distilled (NOT bottled, spring, etc.) water from Walmart. Take a cup of pool water, and add a cup of distilled water. Mix, and test BOTH pH and CYA.

2. While you are at Walmart, purchase (8) gallons of PLAIN 8% household bleach, and (4) boxes of 20 Mule Team borax. Both should be in the detergent section.

3. Assuming that your pH result is roughly the same with the distilled dilution, SLOWLY add a box of borax to your skimmer, while the pump is on and the skimmer operating. (Do not go too fast: borax can solidify into a pipe-blocking solid, if you do!)

4. Continue to add 1/2 gallon of the bleach to your pool each evening -- to 'keep it' while you work out next steps.

5. Read this post: http://pool9.net/bucket-demand/ and do a bucket chlorine demand test, to see 'how far in the hole' you are.

6. Continue to keep an eye on your pH -- if you DO have ammonia, you want the pH higher, rather than lower.

7. Report your CYA test results: it's possible to have very high CYA *and* significant ammonia levels.