Missing CYA

AlexR

LifeTime Supporter
Jul 21, 2011
2
Redwood City, CA
I just tested my water today (Taylor 2006 kit), and my CYA reading is baffling me. I couldn't get any reading. It was basically clear when the vial was full. Now last summer I had added a bunch of CYA and it tested around 50 or so. I double checked with the pool store, and they also didn't see any CYA. So my question is, where did the CYA go? It's my understanding that the only way to get rid of it was to replace water.

We had a wet winter here in Northern California, but it wasn't due to rain dilution as I have a safety cover and use a cover pump to remove the rain off it. The pool store suggested I might have a leak, but I'm pretty sure I would have noticed that in my water bill. Besides, my salt level hasn't gone down much (3300 to 3200). If my water was heavily diluted then I'd expect low salt levels as well. Anyone have any ideas?

Alex
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Hi Alex and welcome to TFP. :wave: While CYA is typically lowered by water exchange, a small amount (3-5 ppm) is oxidized each month from use, not to mention splashout. If it's been about 10 months or so, that could be 40 to 50, not to mention the +/-15 degree of testing variance. Regardless, if you're low, now's the time to add. :)
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
20,401
San Dimas, CA (LA County)
Under certain conditions CYA can break down into ammonia.

Search Ammonia here and you'll find a whole bunch of threads.

What are your test results? Low FC and high CC are a pretty good clue if that's where the CYA went.
 

AimeeH

LifeTime Supporter
TFP Guide
Apr 2, 2012
2,002
Columbia SC
Welcome to TFP

I hope someone else can chime in but I'm pretty sure (last year in particular) we have seen several cases of CYA disappearing over a winter often causing an ammonia problem. You will see a HUGE chlorine demand if that is the case.




And Richard and Texas beat me to it :)
 

AlexR

LifeTime Supporter
Jul 21, 2011
2
Redwood City, CA
Ok, ammonia might be what's going on here. My salt cell croaked recently, so I was running with zero chlorine for some time (not sure when it died). I just installed the new cell Sunday and added some bleach to help to get going. Testing this morning, FC was only 1. I lazily didn't test CC at the time. I of course added some CYA and some more chlorine before reading these replies. Right now, testing after adding some bleach FC is 4 and CC is .5.

I'll see what it is tomorrow morning. If I understand things, I just fed the critters some fresh CYA, so I should expect little to no FC and a high CC, correct?
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
20,401
San Dimas, CA (LA County)
Ok, ammonia might be what's going on here. My salt cell croaked recently, so I was running with zero chlorine for some time (not sure when it died). I just installed the new cell Sunday and added some bleach to help to get going. Testing this morning, FC was only 1. I lazily didn't test CC at the time. I of course added some CYA and some more chlorine before reading these replies. Right now, testing after adding some bleach FC is 4 and CC is .5.

I'll see what it is tomorrow morning. If I understand things, I just fed the critters some fresh CYA, so I should expect little to no FC and a high CC, correct?
Not necessarily. The bleach you added packed a pretty good punch since it wasn't buffered at all with CYA. You might have killed whatever bacteria it is that ate the original CYA.
 

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