CYA Test Question

[Pharmacyman]

Hi,

This is my first question after being registered with the site for a good while. I have always been able to get my questions answered by reading "pool school" or other members posts. Thanks for that. Now I have a question:

I tested my CYA after putting in a new liner and refilling the pool and adding CYA on 5/11/09. On May 18 the CYA was 20. Finally got more CYA last week and when I tested today (5/31/09), prior to adding anymore CYA, the CYA is back to zero. How could this be? I have not backwashed or drained any water. We have had a good bit of rain...pool is up maybe three inches. Should I wait for evaporation to bring the water level down 3 to 4 inches and then retest? Would you add more CYA now?

Thanks and really appreciate the knowledge I have gained from your site,
Ken Keever
High Point, N.C.

 

[Guest]

The lowest the test can reliably read is 20 ppm which is where you were. The dilituion dropped you below that so it's impossible to read where you are now and it could very well register 0 ppm.

IF you have not drained any water assume you have 20 once the water evaproates to it's normal level and add more CYA accordingly to get ot your desired level.

It's really much easier just to compute how much CYA you need and put it in all at once than the piecemeal approach so many seem to take. If you are sure about your pool volume and measure accurately by weight then it will come out right on the money.