Cya readings after winter

Reddogdan

LifeTime Supporter
Sep 17, 2013
246
Mansfield, Texas
So, 2nd year in a row my cya has dropped considerably over the winter. In October it was 60. Now it's below 20.
FC. 7
Cc. 0
Ph. 7.4
TA. 75
Ca. 300
Cya 30 or less
I keep a solar cover on all winter. Where is my cya going? With all the rain I have only drained 2" off the pool. Any ideas?
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
16,023
Tucson, AZ
CYA can be consumed by microorganisms (bacteria & fungi) as an energy source. The end result, if all the proper bacteria are present, is for the CYA to eventually become nitrogen gas and nitrates. If there is not the right mix of bacteria, then you get a really, really bad result - CYA gets converted to ammonia and you have a HUGE chlorine demand at spring startup (it requires the FC needed to be 10X the amount of ammonia in ppm N, so a reading of 8ppm ammonia on an aquarium test kit would require 80ppm FC to neutralize).

The other possibility is winter rain & snow dilution if water is routinely drained from the pool over winter months.
 

BasicTek

Bronze Supporter
Oct 9, 2016
867
Lake Mary, FL
Jeez, less than $2 a pound? That's a great price for it, but I'd never need that much for my little pool, lol.
I've been using my leftover pucks and a couple bottles of liquid the previous pool owners left behind, not sure when I'll actually need that much either but they sell it in all sizes on ebay. With that 25 lb box you can afford to lose more CYA than expected...
 

borjis

LifeTime Supporter
Aug 19, 2014
3,034
Pacific NW
I don't think it goes bad that quickly. Wonder if you got a bad batch?

did you get it from tftestkits? If so you should let them know.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
16,023
Tucson, AZ
There was some bad batches last year. PM OTpirate and she’ll check the batch id.

- - - Updated - - -

There was some bad batches last year. PM OTpirate and she’ll check the batch id.
 

BasicTek

Bronze Supporter
Oct 9, 2016
867
Lake Mary, FL
i bought a bottle of the 50 cya test solution last year. Used it yesterday while I had nothing better to do and it showed 0 cya. Does the solution go bad?
Did you test this last year and it had 50? If using TF100 then 0 could also be 15 right... and how many months... I have some that I bought over the summer. I'll try and test it but I have a taylor kit so 0 could also be 25 in my case. I don't expect mine to still be at 50 but will be interesting to see. I did test it in late summer and it was definitely 50 then.
 

BasicTek

Bronze Supporter
Oct 9, 2016
867
Lake Mary, FL
Getting back to this I just finally tested my 8 month-ish old CYA sample and surprisingly I got 60 not 50 (not sure why, tested 3 times back to sun on birght day), so there goes the theory that CYA just vanishes, there must be something about our pool conditions that is depleting it. Something that is not present in my little plastic sample that has been indoors away from sun and weather for 8 months.