Perplexed by results help?

[travelcat18]

A friend of mine was having trouble getting his chlorine level to register despite using pucks. He said his chlorine was registering zero on a Walmart test kit. He uses pucks a lot during the year and I have been trying to sway him to the TFP side. Anyway I asked him to bring a water sample to work and I would test with my TF-100 and here are the results.

FC 0
CC .5
TC .5

CYA 0

The CYA level blows my mind because he mainly uses pucks, and some liquid to sanitize. I expected it to be crazy high so I did the diluted test to start and it was 0, so I did the non diluted test and still zero. No test error as I did this several times. zero cloudiness with the reagent.

this sample was obtained this morning and kept in a airtight container and was about room temp.

can something else cause the CYA to error? and or chlorine?

he has a roughly 13,000 in ground pool, with sand filter

 

[Donldson]

Sounds like a CYA to ammonia conversion over the winter. Not that unusual, it requires quite a bit of chlorine to break down the ammonia. The best way to clear it is:

1, Add enough liquid chlorine to bring FC to 10 ppm
2, Wait 10 minutes and recheck FC. If below 5 then raise back to 10 and repeat. *This may take a while if CYA was especially high upon closing*
3, Once the FC level holds above 5 add CYA to bring to 20 and continue as a normal SLAM

Take any pucks out until this is done because the CYA is continuing to feed any remaining bacteria and creating more ammonia.

 

[travelcat18]

Sounds like a CYA to ammonia conversion over the winter. Not that unusual, it requires quite a bit of chlorine to break down the ammonia. The best way to clear it is:

1, Add enough liquid chlorine to bring FC to 10 ppm
2, Wait 10 minutes and recheck FC. If below 5 then raise back to 10 and repeat. *This may take a while if CYA was especially high upon closing*
3, Once the FC level holds above 5 add CYA to bring to 20 and continue as a normal SLAM

Take any pucks out until this is done because the CYA is continuing to feed any remaining bacteria and creating more ammonia.

thank you