Testing CYA after sock method

Razorhog

Bronze Supporter
Jun 20, 2013
489
Northeast Arkansas
#1
I put the suggested amount (actually a bit less) in some socks and let it dissolve. A couple days later I tested CYA and it was double the amount I intended - I was going for 30 and it reads 60. Now I know that the general advice here is to wait a week, but I figured if you tested early it would show up lower than your target, not higher. CYA was 0 when I opened. Pool calc said add 4 lbs 6 oz of stabilizer to bring CYA from 0 to 30. I added a little less than 4 lbs because it's all I had. Water is crystal clear but I'll need to do the vitamin C in a sock and rub the stains off the side. Here are my latest test results:

FC - 18
TC - 18
pH - 7.4
TA - 90
CA - 50
CYA - 60

So my question is - Could testing too soon after the CYA is dissolved cause higher readings? I tested water from two areas of the pool. Pump is running 24 hrs/day during start up. Thanks!
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
#2
No need to wait longer. We dispelled that myth last season in numerous tests. Once dissolved, your CYA should be very close to what you projected within 24 hours. So in your case of over-shooting your target, that would typically leave one of the following items to consider:
- Either the initial test was off, or the post-addition test was off; maybe one or the other wasn't conducted under a bright, sunny day?
- Dosage - but you confirmed that already

You stated when you opened it was zero, but the viewing tubes only go down to 30, so anything below that is very difficult to determine. For example, if you actually had 15ppm in the water (almost impossible to read), then had a +/- 10-15ppm variance in the test (possible), that could get you very close to what you're seeing now.
 
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Razorhog

Razorhog

Bronze Supporter
Jun 20, 2013
489
Northeast Arkansas
#3
No need to wait longer. We dispelled that myth last season in numerous tests. Once dissolved, your CYA should be very close to what you projected within 24 hours. So in your case of over-shooting your target, that would typically leave one of the following items to consider:
- Either the initial test was off, or the post-addition test was off; maybe one or the other wasn't conducted under a bright, sunny day?
- Dosage - but you confirmed that already

You stated when you opened it was zero, but the viewing tubes only go down to 30, so anything below that is very difficult to determine. For example, if you actually had 15ppm in the water (almost impossible to read), then had a +/- 10-15ppm variance in the test (possible), that could get you very close to what you're seeing now.
Thanks for the reply. Good to know about not needing to wait a whole week. The difference might be that the second test was done with old R-0013 that I bought in May of 2014. It has been kept in a dark indoor closet - does it go bad? I'll do the test again with the R-0013 I got last spring in my TF-100 kit. I wish there was a more precise test that would determine lower levels of CYA.

Both tests were done with my back to the sun. First test the water was super clear just like it is on my first test every year and I assumed it was 0. I've always hit my target assuming 0 at opening. Maybe I didn't drain as much excess water over the winter as I usually do, not sure. Good news is that I can live with it at 60, I just prefer it lower to save on bleach.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
20,330
San Dimas, CA (LA County)
#4
Thanks for the reply. Good to know about not needing to wait a whole week. The difference might be that the second test was done with old R-0013 that I bought in May of 2014. It has been kept in a dark indoor closet - does it go bad? I'll do the test again with the R-0013 I got last spring in my TF-100 kit. I wish there was a more precise test that would determine lower levels of CYA.

Both tests were done with my back to the sun. First test the water was super clear just like it is on my first test every year and I assumed it was 0. I've always hit my target assuming 0 at opening. Maybe I didn't drain as much excess water over the winter as I usually do, not sure. Good news is that I can live with it at 60, I just prefer it lower to save on bleach.
The daily bleach usage shouldn't be any higher. It might actually be a little less. It's just getting the FC up to the target the first time that takes a bit more.
 
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Razorhog

Razorhog

Bronze Supporter
Jun 20, 2013
489
Northeast Arkansas
#5
The daily bleach usage shouldn't be any higher. It might actually be a little less. It's just getting the FC up to the target the first time that takes a bit more.
Ahh I see - so getting to my target of 8 (if CYA is 60) will take a bit more but I'll still need the same amount or less to maintain assuming the same bather load and whatnot as usual. I just don't want to let it drop lower than 5. And if I need to shock it will take more to get it up to 18, but I don't generally need to shock. Thanks
 
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Razorhog

Razorhog

Bronze Supporter
Jun 20, 2013
489
Northeast Arkansas
#7
Just thought I'd report back that the pool company did put stabilizer in. Being sick I didn't even talk to them so I didn't know. That's how I ended up basically doubling CYA... Anyway I'm good now.
 
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Razorhog

Razorhog

Bronze Supporter
Jun 20, 2013
489
Northeast Arkansas
#9
That would do it! Did they open the pool for you?
Yes I have them open and close. Open they get me started but have never added stabilizer. Go figure! They store and clean my cover, replace all drain plugs and fittings, vacuum, brush, make sure pumps are working,etc over a few days. Replaced a bad breaker for me this year. After opening they just leave me to it, works well.