CYA doesnt build up as fast as people think??

[boon4376]

Either my Taylor test kit came with defective CYA measurement tests or CYA naturally declines or does not increase as fast as people say it might.

I used about 20lbs of Cal-Hypo to open my pool and have been using about 1lb of Dichlor / week for chlorinating and my test kit still reads 0 CYA...
And it says that the mixture is supposed to turn cloudy when I add the chemical to my test sample, however it remains perfectly clear.

Now one reason I am worried is that even with a 2-3 ppm free chlorine and a 0.2ppm of combined chlorine, I can add enough liquid chlorine (bleach) to boost things up to 6-7ppm and if I leave the cover off my pool for an afternoon, by the evening my free chlorine will be completely gone, indicating that I may really have no CYA stabilizing any of my chlorine against sunlight... Which would mean that it is very costly for me to be using plain old unstabilized chlorine as it is only remaining effective for very short periods of time, at most the ~12 hours if I add it in the evening.

I know that I do not have a contaminate lowering my FC because the water is crystal clear and my CC hasn't been above .2 ppm.

I know the last people who lived here used Cal-Hypo exclusively so I would have thought that the CYA levels would be really high to begin with, however pool company tested it as only 30 when I opened it, and it seems to have declined.

So I'm just confused overall. I've been using Dichlor (~1lb)when I want to bring the chlorine up far for when I know I'll be away for 3-4 days; and I just do a nightly bleaching with liquid chlorine (~1/8th gal?) to maintain a level of FC to keep things sparkling.

Havnt had any algea problems anyways, however I did go a little crazy with algeacide when I opened it and I've put borox in to increase the PH which I've been told acts like an algae preventative anyways.

(Been open about 6 weeks)

 

[Butterfly]

We would like to see a full set of water test results.

The cal-hypo contains calcium, but not CYA. The dichlor does contain CYA.
You can use the PoolCalculator.com to see how much CYA you have added to your pool based on the amount of dichlor you have added.

I know that I do not have a contaminate lowering my FC because the water is crystal clear and my CC hasn't been above .2 ppm.

There is a bacteria that eats CYA. Kinda rare, but happens often enough. The answer is shocking the pool using Pool School methods.

You should do the OCLT to help confirm yea/nay organics.

 

[JasonLion]

Five applications of one pound of dichlor will raise CYA by 19 in 16,000 gallons. The CYA test can register levels as high as 20 as if they were zero, so if I guessed about right on your use of dichlor five times then your results don't seem at all surprising.

 

[anonapersona]

With the strips I was using, it can read 30 ppm of CYA as 0.

 

[jnd5309]

boon - I had a similar problem. After following the Pool School article for opening a seasonal/temporary pool to a tee, I used dichlor as suggested in that post -- and at the end of a week had no measurable CYA. I added a small amount of CYA in a sock -- a week later still nothing. I knew I had some stabilizer in the water, because all of my chlorine wasn't going away during the day, but I couldn't get a measure on it. So I posted my numbers on here and sure enough I got the suggestions I needed and finally I'm at 30 ppm. The TF-100 test kit doesn't measure CYA below 20, I obviously had some but less than 20. I went back to the pool calculator, told it I had 15 ppm, and added the recommended CYA. Happy to report I have clear, sparkling water now with a FC level consistently at 3 ppm with CC of 0. It will work if you follow the Pool Calculator!