Not good at Chemistry

New2water

LifeTime Supporter
Jun 28, 2011
78
Stockton, CA
I'm not good at Chemistry so can use a bit of help. I have been using the Bleach part of the BBB method so far. Here are my test results:

FC: 15.5
CC: 0.5
TC: 16
pH: 7.5
TA: 82
CH: 220
CYA: 20

Last year my CYA was way high and I had to completely drain the pool. My understanding is that CYA can only go up but I am seeing it going down. It was about 40 last month. What could be the reason? I don't want to add too much stabilizer and drain the pool again. The Pool Calculator suggests the following:

Increasing TA: Add 94 Oz by weight/75 Oz by volume Baking Soda,
Increasing CH: Add 118 Oz by weight/95 Oz by volume Calcium Chloride (don't know what that would be in BBB terms),
Increasing CYA: Add 53 Oz by weight/56Oz by volume or 138 Oz liquid Stabilizer.

Just want to confirm from experienced people if this is what I should be doing?

Thank you.
 

JasonLion

TFP Expert
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LifeTime Supporter
May 7, 2007
37,879
Silver Spring, MD
Is there a reason your FC level is so high?

The CYA test is not all that precise. It is more likely that there is some testing error, rather than CYA falling that much in only a month. About the only thing that could bring it down that much is a slow leak. Another way to get an idea if there is testing error is noting how much of your chlorine you lose during the course of a sunny day. With CYA around 20 you should be losing 3/4 or more of your starting FC level through a sunny day, while with CYA around 40 it would be 1/2 to perhaps 2/3.

TA is fine where it is.

You should indeed raise CH, though that isn't necessarily your first priority.
 

J20832

LifeTime Supporter
Jul 3, 2009
218
Olney, MD
What test kit are you using? Just want to confirm the reliability of your measurements as data from pool story tests and strips can vary greatly...

Anyway, based on your results (and BTW, I am still scratching my head on how you arrived at a TA of 82),

Leave the TA alone. "82" is fine. (but you should question that reading).
Yes, increase the CH, but my calculations show 213oz to get to 300ppm.
Yes, increase the CYA, but again, I think your amount is low, I get 72 o. to get to 50.

Anyway, I don't blame you for being cautious with the CYA, you could always add half and retest in a week.

Your CYA could have gone down a lot if you had a lot of rainfall and had to pump out some water or you had water overflow your pool. Also, your previous testing could have been erring on the high side...
 

New2water

LifeTime Supporter
Jun 28, 2011
78
Stockton, CA
I am using TF-100 kit and the TA of 82 is a type. It was 80.

FC is so high because I observed some algae forming and I dumped 4 gallons of Sodium Hypochlorite (10%). I assume this is concentrated version of Bleach sold at Home Depot (which not much more expensive than store brand bleach). In my mind, I was 'shocking' the pool. I must have overdone it.
I lose about 2/3 of FC through the day and there is no leak in the pool. I tested it by shutting off the water supply. There is some loss because of evaporation.

FYI, my pH was previously a little over 8 and I had to add 4 gallons of MA to bring it down.

I will add some stabilizer and test in a week as recommended. Haven't had any rain this year in Stockton, CA other than a few sprinkles.

Thank you for the prompt advice.
 

New2water

LifeTime Supporter
Jun 28, 2011
78
Stockton, CA
I ran my tests again today and am surprised to see a big change in T/A from 80 to 150 in a month's time. Similarly CH has gone up from 220 to 260. I haven't added anything other than Sodium Hypochlorite (10%). My test kit doesn't provide a way to accurately measure pH other than the K-1000 kit's dual tube estimation procedure. It is more purple than the highest level color of 8.2.
I am seeing some stains in various parts of the pool and am afraid it may be leaching calcium. Should I add calcium which I can get in the form of Excel Calcium Chloride pellets from the local Fastenal store?
 

duraleigh

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In The Industry
Apr 1, 2007
34,428
Sebring, Florida
You absolutely need to lower your pH and get it into the 7's and keep it in the 7.5 range. Disregard your other issues until your pH is lowered and kept lowered.