Help with Water balancing

[ngc4900]

Hello
I just received my new TF-100 refill kit yesterday (all new reagents) and did comprehensive testing of my pool water today. I did a partial drain (70%) in April 15. I tested the CYA three times since I drained the pool and got 20-30 range. I only use bleach for my CL source.

Here are my results:

FC-3
PH-7.5
CC-0.5
CYA- 0
TA - 90
CH - 200
Water Temp - 87F

my concern is the CYA. Prior to doing a partial drain, my CYA was about 50. Now it is zero, the CYA reagent added to the pool water is almost crystal clear. Therefore I postulated that the new R13 reagent that came yesterday was defective. So I used another bottle from last year (APR 2015) and got the same results. My worry is that an indoor pool should be accumulating some CC since it has no sunlight to burn it off.

What, if anything am I doing wrong, and what do I need to be concerned about.

Thanks

Best

Joe

 

[kimkats]

Trust your test kit.........My guess is that your CYA is low. It might not be 0 but it is low due to the drains.

When you add CYA go slow in how much you add so as to not overshoot your goal.

Kim

 

[Texas Splash]

Joe, I want to make sure I'm reading the sequence of events correctly. "Before the 70% drains last year, the pool was originally at 50. After the 70% drains you got it down to the 20-30 range. You did the testing yourself back then and recently. Am I correct? If so, before we assume the reagent is bad, let's say you had only 20 ppm. There's a +/- 15 ppm variable on that CYA test, so it could have been much lower than anticipated I suppose. But even if it was 20 after testing 3 times since Apr 15, even when optimally managed, CYA will degrade and slowly become consumed/eliminated over time. In your indoor pool that may only be about 2 ppm each month, but over 6 months that would be almost 20. Add that to any splashout and subsequent water replacement, perhaps that could account for the very low (if nothing) recorded now?

 

[pooldv]

Agreed, you will lose a few ppm each month. And 30 is really the lower threshold for being able to reliably test/read CYA. Was the sample water cloudy at all? If yes, then there was some CYA present. If clear then probably not. I believe that chlorine will also consume CCs.

 

[ngc4900]

Thanks for the help. The water was clear.
Thanks

Best

Joe

Agreed, you will lose a few ppm each month. And 30 is really the lower threshold for being able to reliably test/read CYA. Was the sample water cloudy at all? If yes, then there was some CYA present. If clear then probably not. I believe that chlorine will also consume CCs.

- - - Updated - - -

Pat,
You got all the information correct. I think you are right. My CYA was probably lower than what I reported after the drain and probably lower after splash out, water replacement, and degradation.
Thanks

Best

Joe

Joe, I want to make sure I'm reading the sequence of events correctly. "Before the 70% drains last year, the pool was originally at 50. After the 70% drains you got it down to the 20-30 range. You did the testing yourself back then and recently. Am I correct? If so, before we assume the reagent is bad, let's say you had only 20 ppm. There's a +/- 15 ppm variable on that CYA test, so it could have been much lower than anticipated I suppose. But even if it was 20 after testing 3 times since Apr 15, even when optimally managed, CYA will degrade and slowly become consumed/eliminated over time. In your indoor pool that may only be about 2 ppm each month, but over 6 months that would be almost 20. Add that to any splashout and subsequent water replacement, perhaps that could account for the very low (if nothing) recorded now?