CYA went down as I decreased TA and increased CH

[Isotfp]

Hi all,

Newby. Houston in-ground chlorine pool - not sure the capacity. I have to get off my duff and calculate it. It's somewhere between 11,000 and 16,000. Pebble/plaster. Two years old.

Anyway, I just decided to take a more active role in managing pool chemistry. The 2-year old strips were WAY off.

I bough a Taylor K-2600c and the CYA was off the charts. 4 drain/fill cycles later (1 foot at a time) and it was down to 45.

What was odd: I then corrected TA and CH, which went find, but the CYA went down in doing that.

So I'm wondering if the CYA test reacts to TA and/or CH somehow.

I'm on the right path, I thought I would just leave a note: if your CYA is real high, you might make sure TA and CH are where you want before believing the CYA number, if you're using the K-2600C.

Thanks for all the great info!

 

[mknauss]

Welcome to the forum!
TA and CH have no effect on CYA levels.
Your test results show a 40 CYA. Remember to round up if you fall between 30 and 40.
Can you fill out your signature? Really helps us help you.
I suggest you read ABC's of Pool Water Chemistry.

 

[Isotfp]

Thanks. I figured they didn't affect one another. What I am wondering is if they affect the K-2600C CYA test itself. I was pretty thorough and repeated the test several times and it clearly went from 45 (50?) to 35 (40) with no addition of CYA (was chlorinating with cal-hypo), but with 3 gallons of 31.45 muratic and 35 lbs of calcium chloride.

 

[mknauss]

What I am wondering is if they affect the K-2600C CYA test itself.

No. They do not effect the CYA test at all.

Variation of +/- 10 ppm CYA is well within the normal for that test.

 

[Isotfp]

Interesting. Operator error?

 

[mknauss]

The test is in no way precise. As you do it over time, you will get more repeatable in your method.

 

[jseyfert3]

There is a 50 ppm CYA standard solution you can get to check your testing technique on the CYA test if you'd like. I got it when I was wondering if I had been "reading" the test correctly. Turns out I had been, but it was well worth the peace of mind for a $6 add-on to a TFTestkits refill order.

 

[Chasarms]

How much time elapsed between your first and second test? CYA does degrade, the hotter the conditions the more so it does. And, you're in Houston.

I lose 4-5 ppm per month.

 

[borjis]

Another point of mention:
Very cold water below 70 degrees f will give a false high reading for cya.

Not the case here, but worth mentioning.

 

[batesjer]

70 degree water means pools open in our neck of the woods.