Where has the CYA gone?

[pcmacd]

I drained/filled my Phoenix pool just about a year ago using a Mesa city water source delivered by truck (I'm on a shared well and can't use it for that.) That Mesa water has lots less magnesium sulfate than my well-based makeup water does.

Oh, and? My well water is a fantastic laxative. I'll send you a quart for free if you pay the postage! You know how long and how many "OH S***S!!!" it took to figure that out? :-( I really hate handwashing u-trau.

I lost my pool management records from that time, but I'm sure I had my CYA up to about someplace betwixt 70 and 80 ppm. I had put _at least_ 12# of dry CYA in for my 18.2K gallon pool. I had AT LEAST 3 ea. 4# bags, perhaps one more, from Leslie's.

I have backwashed my filter 2x or 3x since then (the pool does not get lots of use, and I bump the filter), so I can't imagine that I've tossed more than a couple hundert gallons out of an 18.2K gallon pool.

Where did the CYA go? Leslie's did a test which said 51 PPM. I din't believe it.

I did my own test today with the TF-100 kit R-0013 reagent and got 50 ppm, so the the results are consistent (which actually astonished me, as the CYA test is oh, so severely subjective!)

I hesitate to add the four more pounds of CYA which the calculator says would bring me up to near 80 ppm until I am sure of what in the freakin' what is going on?

All that being said (written?) my new SWG at 70% runtime of around 8 hours/day is having a hard time keeping the FC above 6 ppm.

--->> Which suggests, again, that my CYA might be suffering.

I remain, bewildered here.

I get my water samples about a foot under, in the shade, around 4 PM afternoons when the pump and SWG are not operating.

• I'd take the samples deeper but I'm not a chimp nor a skyhook.

tanks

mac

 

[YippeeSkippy]

Interesting..... last year or the year before we had a few folks say their CYA disappeared and we sort of scratched our head and wondered it there had been a bad batch of CYA or something?? Do you recall the brand?

Only thing I can tell you is to get some more and hope it stays. Add 10ppm at a time.

Maddie

 

[mknauss]

CYA degrades over time. About 5 ppm per month, except in our climate, I can see 10 or 15 ppm per month when the water temperatures are at or above 85F. I do not find it surprising at all that your CYA has dropped by that much over a years time.

 

[CrystalRiver]

You should be collecting samples when the pump is running, away from any returns.

Other than that, everything sounds normal. CYA does degrade over time, about 5 ppm per month. Go ahead and add that CYA in a sock.

 

[YippeeSkippy]

Ah ha! You're right Marty- the OP is in YOUR neck of the world. I too can imagine heat having an effect on CYA.

Good catch, Marty

 

[pcmacd]

Interesting..... last year or the year before we had a few folks say their CYA disappeared and we sort of scratched our head and wondered it there had been a bad batch of CYA or something?? Do you recall the brand?

Only thing I can tell you is to get some more and hope it stays. Add 10ppm at a time.

Maddie

It was from Leslie's.

 

[pcmacd]

You should be collecting samples when the pump is running, away from any returns.

Other than that, everything sounds normal. CYA does degrade over time, about 5 ppm per month. Go ahead and add that CYA in a sock.

Geez. Iben told over and over that CYA never goes away. I'm not doubting you, sir, this is just really new information.

 

[trivetman]

CYA does go away slowly….just not nearly as fast as a steady diet of trichlor pucks adds it