What would you do? Cya dropped rapidly!

Iam1964

Well-known member
Dec 26, 2019
79
Conroe, Tx
Hi guys,

my cya has been a very constant 50 from the end of December and I have been testing it about twice a month. 2 weeks ago I had our local pool company do a water test for me using there fancy electronic 10 test machine and everything was in line with my tests.

Last night I tested my cya and it had dropped to less than 30. I can fill the tube and still see the dot.

I took a sample to the pool company and they again done a full gambit of tests and again everything was in line with my own testing but this time the cya was 43.

So at this stage, what would you do?

thanks
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
32,631
Laughlin, NV
You cannot read a level of 43 using the CYA test. If over 40, it is 50. I suspect you may have had some rain overflow that has diluted your CYA level just a bit. When it lower to 40, then add 10 ppm worth of CYA.

Edit - sorry, I see you say it is 30ppm. Add 20 ppm worth of CYA. Do not trust pool store tests. Quit getting them, they are just confusing.
 

Iam1964

Well-known member
Dec 26, 2019
79
Conroe, Tx
Marty, seemingly Leslie's pool store can now measure to better resolution than the Taylor test. The test is now done in a pretty expensive electronic machine.
Allen, I do have an overflow but not an auto-fill. We have had some rain but I didn’t think it was enough to make such an impact. I have been wrong before though...... many times ?
 

Iam1964

Well-known member
Dec 26, 2019
79
Conroe, Tx
Marty, I need to continue with the pool store test as it is required for the equipment warranty. I don‘t mind doing this as their tests have been completely in line with my own testing up until now.
 

PoolGate

Gold Supporter
TFP Guide
Jun 7, 2017
4,833
Damascus, MD
1 errant test is not an indication to panic. I'd test again with a sample from another part of the pool. Operator error could be a suspect in the store test as well as your own. CYA does degrade over time and has to be replenished.
 

cfherrman

TFP Guide
May 10, 2017
2,527
Hays, Kansas
Get your pool store tests but don't even bother with them, just file away.

Time and Time again pool store tests are wrong.

Just retest your cya, make sure you are testing it the same way each time with the same light conditions.
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
14,453
Evans, Georgia
Fancy machines are theatrics. If they don't calibrate it often or properly it will be off. If the technician is in a hurry, the test can be off. If your sample sat in the car for a few hours, some tests could be off? Do they suggest you buy x, y and z chemicals after they test??

Doing your own reliable tests, which can be repeated with the same results, is better than a pool store's fancy machine any day, in my opinion.

Maddie :flower:
 

Iam1964

Well-known member
Dec 26, 2019
79
Conroe, Tx
I’ve tested the cya 4 times now and it is < 30. To give some credit to the pool store guy, he has never asked me to buy anything so far and his results have always been in line with mine except this time with the cya. I think I will add 10 ppm and remeasure.