TA and CYA Common “Misconceptions”

Katygreys

Gold Supporter
Mar 5, 2022
218
Katy, TX
Pool Size
18000
Surface
Plaster
Chlorine
Liquid Chlorine
I’ve learned a ton on this forum. Really, a ton. After only 4.5 short months here, I’ve noticed several other posts with the same …let’s call them “misconceptions” …that I initially had at some point. I’ll describe them below and offer my thoughts. Of course, if I’ve gotten any of this wrong, please let me know (I know folks here can be shy ;) )

1. TA
Pre-TFP, I wanted to stabilize my pH; it always crept up. I read that TA is a buffer for pH and can help to stabilize it and slow the drift of pH. My misconception was that the more TA I had, the more stable my pH would be. So I actually bought baking soda from Home Depot and dumped in several pounds, aiming for the highest end of the range. I didn’t realize that lower TA would stabilize pH lower and higher TA would tend to stabilize it higher. Maybe this was a silly oversight, but I’ve seen some questions and posts on the forum from newbs that suggest they had the same misconception I did. For whatever reason, I did not pick up on the details of the TA/pH relationship in all my reading. I eventually realized this after reading many responses to TA question posts.

2. CYA
My initial reading and understanding was that once CYA is in your pool, it’s there to stay, except for splash out and refill due to rain (not evaporation). Only after I began seeing crazy FC loss (and confirmed no organic action via passing OCLT) did I follow someone’s suggestion to re-test CYA. I was shocked to see my CYA reading was 20ppm lower than previously measured 8 weeks before. And only after more reading and some posts did I discover that CYA degrades as temps near and exceed 90 degF. This info is out there, but it’s not in the “executive summary” of CYA. And being in Houston in a terribly hot summer, this seemingly lesser known CYA tid-bit is really a big deal. And to be honest, it got me wondering if this is how pool boys in hot climates get away with the puck method. My guy was using 2 tabs/week last summer. In my pool that adds 15 ppm CYA per month. And from what I read in the forum, one could potentially see degradation of up to 10ppm/month from water temps above 90 deg. So the net increase in the hottest months might only be 5 ppm. …In any case, please don’t mistake my cerebral musings as endorsement of pool boys or trichlor worship and ban me from the forums for blasphemy. Just some observations and thoughts.
 

Cetanorak

Active member
Jun 13, 2022
32
Wimberley, TX
Pool Size
20000
Surface
Plaster
Chlorine
Liquid Chlorine
And only after more reading and some posts did I discover that CYA degrades as temps near and exceed 90 degF. This info is out there, but it’s not in the “executive summary” of CYA.

That is revelatory information regarding CYA for my situation. I have another thread going about the Texas-based, trichlor-fed pool that I inherited with the purchase of a home. CYA and FC are extremely high and since we are in stage 3 drought, there will be no draining and refilling to correct this issue any time soon. I put the solar cover on last week and have noticed that water temperatures are now in the upper 90s.

The solar cover will hopefully slow evaporation loss (which would further concetrate the CYA ratio, until a top-off) but is there any reason why the solar cover would slow the degradation of CYA, even if the water and air temps are high day to day?
 
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Lake Placid

Well-known member
May 27, 2021
240
St. Louis
Pool Size
17000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
That is revelatory information regarding CYA for my situation. I have another thread going about the Texas-based, trichlor-fed pool that I inherited with the purchase of a home. CYA and FC are extremely high and since we are in stage 3 drought, there will be no draining and refilling to correct this issue any time soon. I put the solar cover on last week and have noticed that water temperatures are now in the upper 90s. The solar cover will prevent water evaporation (which would further concetrate the CYA ratio, until a top-off).

Is there any reason why the solar cover would slow the degradation of CYA, even if the water and air temps are high day to day?

”Chlorine breakdown in sunlight causes CYA degradation by hydroxyl radicals. This can cause a loss from 2 ppm per month to 10 ppm per month depending on the amount of sunlight the pool is exposed to.”

Based on the above reading, the solar cover would slow degradation. To what degree - experts need to weigh in.
 
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Toxophilite

Silver Supporter
Feb 23, 2022
816
Dickinson, Texas
Pool Size
15500
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Plaster
Chlorine
Liquid Chlorine
One thing I've noticed, and being just south of you, was on that CYA loss my loss rate was much higher when there's a good bit over 90-degree pool water and days of straight sun, 100 degrees and over. My CYA loss has lately slowed as temps lowered a tad and more cloudy days. Last few weeks, I've lost nothing measureable, and expect no more than 5ppm loss, whereas previously was 10ppm loss in a month. My takeaway is that CYA loss won't really ever be enough in the long term to factor much into my maintenance. I'll never buy CYA until I get my SWG and use my tab feeder when I need it.
 
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