One year BBB, NO CYA at all, How much to add?

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T

Technigogo

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LifeTime Supporter
Jul 28, 2011
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Austin, Texas
I bought this house a little over a year ago. CYA was a 70-80 from heavy Tri-Chlor use. I drained 2/3rds of the pool to get the CYA down and then learned at the first half of last summer that I could not keep up with chlorine demand with tabs, etc. I found this site and switched to BBB. At that start point, I had a CYA of 50ish. I have been chlorinating with bleach based on that number, keeping the chlorine level between 4-8ppm. We use LOTS of chlorine and today, I tested my CYA and much to my surprise, it's 0. Yes, zero, or at least not detectable. This certainly explains the high chlorine usage.

Shame on me, I really didn't think the CYA would change all that much from just adding water due to evaporation, backwashing, draining off some after big rains and such. Obviously I was wrong. I was not checking my CYA regularly. In fact, I don't think I have checked it since end of summer last year.

So, after feeling like CYA is BAD last summer, now I'm left without the knowledge of how much is GOOD. Please advise.

I am in the process of adding Borax (lowering the TA and aerating to get the PH back up). I have long term plans for a SWG but I don't know if that will make the budget this year.


Pool is:
plaster
30,000 gallon
BBB
TF-100 test kit
 
Sometimes over the winter in a closed pool, the CYA is lost/converted. Always good to check in the spring when you open.

Safest would be to assume you are at 20ppm and add another 20ppm. Wait a week and test to see if it registers and then make another adjustment if required. Recommended range is 30-50ppm.

Using poolcalculator, in 30k gallons of water to add 20ppm of CYA, you need 5 pounds of the solid/granular CYA. Put it in a sock and hang it in front of a return so it mixes. Give it a few squeezes when ever you walk by to get it dissolved.
 
I try to test CYA at least every other month, or at least once on a record page that holds 30 tests. That may take longer in winter as I do not test often so it may go a bit more than two months then. I test more CYA more often around vacations because I am always hoping to have the luxury of using trichlor tabs in the feeder instead of depending on the son-in-law to test and add bleach on his way home from work.
 
Update:

I have dissolved 4 lbs of CYA and brought my CYA count up to 20 PPM. I will add 2 more lbs to get to 30, I hope, and retest.

My side project is the Borax addition. I have reduced my TA from 100 to 70-80 now and brought my PH back up to 7.2 so far with aeration from the spa. Hopefully with continued aeration, I can see the 7.4-7.6 recommended PH from the borax "how to" and move onto the next step!

Thanks again for your advice!
 
If your FC was that high and you had zero CYA - I'm guessing hair felt dry and skin felt dry and your bathing suits faded quickly - unless maybe you had just under 20ppm and it wasn't really quite zero in which case it would not be quite so bad.
 
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