I'm at a loss. Requesting help from the experts here.
I have been running my pool for 2 1/2 years now. I have had issues with low Cl this year. Just replaced the salt cell a couple months ago. A few weeks ago I had begun a SLAM process due to high Cl demand. At that time I tested the CYA to get the shock value. It was 40, low, but I didn't see the need to raise it before entering the SLAM process due to advice I have seen here. Had to end prematurely due to a weekend out of town, and it was taking longer than I thought it would. After limping along through a couple of pool parties I am now entering the SLAM process again. I am not quite holding a Cl level with the SWG set on 80% (Digital Nano), which is way too high.
So, I tested the CYA yesterday to get the initial value for the Cl. And.......0, yes 0. I know it was night, but the sample was completely clear. My reagent is < 1 year old and having talked to our very knowledgeable TF100 supplier, this is one of the more stable reagents. I have had problems with the CYA slowly sliding down in the past, but nothing like this. So, now the troubleshooting:
1. It is not a leak (been there, done that) If it was, doubtful it would have gone that low that fast anyway, and I am not adding anywhere near that kind of water.
2. Test operation. I have repeated the test, same result.
I added what I had yesterday and got more today.
What in the world could destroy the CYA like that? Or what am I missing?
The water is clear, always has been.
Cl - 22 (I wanted to make sure it was still above shock value when I got home due to the low CYA level)
CC - 1
CYA - 0
Salt ~ 4000 (I know it is high)
TA - not current
Thanks in advance for any help.