Cya mystery

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blazin

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Jul 29, 2017
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Franklin, MA
Back story I added

2lbs 8/21
2lbs 8/23
2lbs 8/27

CYA makes no sense..
Shocked for the first time last night, I assumed my cya was ~40 even though it measured 25 because of the delay I've seen previously

Target was therefore 17 ppm

This morning I was at fc 16 ppm and cc 0

Tonight:

FA 7.5ppm
pH 7.4
TA 90ppm
CH 240ppm
CYA 20ppm???

It's been 7+ days since 4 lbs have been added so pool math says 28 ppm and my gallons on pool math are high at 17000.

So reading lower today than last night and having added 6 lbs to my new pool says at least 42 in pool math

I'm lost, any ideas? Bad CYA?
 
Have not heard of that brand but as it is 100% Cyanuric acid it should be good. And you added it such that it should all be in the water.

Next item is testing method.

When you do the CYA test, try this next time.

Once you have your solution ready, back to the sun, etc. Fill the vial to a line, say 80, lower the vial to your waist level and glance for the dot, you see it, add solution to the 70 line, glance, see it, repeat until you no longer see it with a glance. Then use the CYA value one step above the line you read. So if you stopped at 50, use 60 ppm CYA.

The vial is in logarithmic scale. So it is not viable to interpolate between the lines. Just use the whole numbers, such as 50, 40, 30, ....
 
Got it, I've got great visual acuity so I'm probably looking too hard.

Does my fc loss during the day align with a higher cya ppm? Ie I lost ~1/2 over 12 hours.. I understand that's harder to answer but I'm hoping its just my method and that the source of the cya isn't at fault

- - - Updated - - -

borjis said:
Did the cya dissolve completely yet or is it still sitting there?

1 pound of dissolved cya in my 13,000 gallon pool raises it around 10ppm.
Click to expand...

It's all dissolved, 4 lbs has been disolved for about a week, 2 additional dissolved for 3 days at this point
 
You lost 0.5 ppm FC during the 12 hours of daylight? That is quite low. I know you are up north but I would suspect your normal loss would still be near 2 ppm FC per day.
 
That is pretty high loss. I would suspect you should not be ending your SLAM.

All three criteria passed?
 

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The one thing about CYA -- if you added it it is in the water.

The last variable is pool volume ------------
 
mknauss said:
The one thing about CYA -- if you added it it is in the water.

The last variable is pool volume ------------
Click to expand...


Ok that's what I figured from everything I've read, specifically things I believe you have posted!

That's why even though my test said "25 ppm" my math told me 42ppm, so i targeted my SLAM at 17 ppm FC.

I'll try the quick glance test 9/3 which will be a full week after dissolving the last 2lbs for a 6 lbs total. Until then, I'll continue to keep my target FC level between 5-7ppm
 
AquaMate is the brand that I added and added and added some more and the CYA just wouldn’t go up. Ok, it went up maybe 25% of what it should have, if that. I did this for two years. I was a noob, but I guess I was also a slow learner. I switched brands and CYA went up as expected.
 
Deb04 said:
AquaMate is the brand that I added and added and added some more and the CYA just wouldn’t go up. Ok, it went up maybe 25% of what it should have, if that. I did this for two years. I was a noob, but I guess I was also a slow learner. I switched brands and CYA went up as expected.
Click to expand...

Did you get yours from ocean State? Noticed you're in range..
 
JimMarshall said:
That’s an awfully accurate figure for pool volume. How was it arrived at? Are you sure that it’s accurate?
Click to expand...

Figure probably came from the PB or upon initial fill or subsequent fill. The pool company actually did not give me what my pool volume actually was. They were kind of confused. Originally, it was 14,700 gallons. I actually went back to the my water bills, upon fill up which was all within that month, and it is either 14,700 or 15,700 because I consumed about 1,000 gallons more. Originally, I was going to change my figure to the higher, but it was been at the 14,700 for so long, that I left alone in my signatures.

Most people, IMO believe their pool is actually larger than it is. They are usually off by about 5,000-8,000 gallons. It must be a PB thing where they tell the customers you are getting a bigger pool, which is what people want. Personally, I would not have wanted a bigger pool. More water, more of everything. It is just right.
 
JimMarshall said:
That’s an awfully accurate figure for pool volume. How was it arrived at? Are you sure that it’s accurate?
Click to expand...

My signature is pool builder, my pool math has been using 17000.

Unless my volume is low.. I can't see how what I've added should read low unless it's still dissolving, I'm being too critical of the black dot contrast eye chart, or the potency is low on the cya.
 
blazin said:
My signature is pool builder, my pool math has been using 17000.

Unless my volume is low.. I can't see how what I've added should read low unless it's still dissolving, I'm being too critical of the black dot contrast eye chart, or the potency is low on the cya.
Click to expand...

Through the years, there have been members who experienced the same issue with certain brands of CYA. Personally, I have used the sock method with powdered HTH, and it dissolves real quickly, which 100% accuracy. Over the last few years, I have gathered some friends and purchased the liquid Natural Chemistry in bulk (over 20 gallons), of course split many ways in where we were able to purchase for like $17 on sale per gallon. It is quick, no hassle and without any problems. Yes, a little bit more on price, but I save in other ways. The pool stores sell for close to $40 a gallon. That is a free delivery no tax type of deal.
 
blazin said:
My signature is pool builder, my pool math has been using 17000.

Unless my volume is low.. I can't see how what I've added should read low unless it's still dissolving, I'm being too critical of the black dot contrast eye chart, or the potency is low on the cya.
Click to expand...

There is a way to test your input volume. At night when the sun is down, rest FC and add enough chlorine to produce a 10 PPM rise, wait 20-30 minutes to circulate, and report back the actual rise. Use the 25 mL test for accuracy.
 

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