TA okay? Choosing target FC while adding CYA.

[Amy.M]

I started on Saturday with 100% new fill water. (Thanks for walking me through that!) I plan to switch to SWG once I hit the levels recommended in the Water Balance for SWG's post.

My current numbers are:
TC - 8
FC - 7.5
pH - 7.2
CH - 50
TA - 110
CYA - added stabilizer today, will test in a week

I'd like to add borates using the boxes of Borax I have left over from last year. The TA of 110 is higher than recommended, but Pool School says not to worry about lowering TA just to hit a target number. I have no concern with CSI, and have not had past had issues with pH drifting up. Is it okay to start slowly adding borax in increments without worrying about the increase to TA (30/box in my case)?

During this week I am waiting to test CYA, do I maintain chlorine levels appropriate (per the chlorine/CYA chart) for the amount of CYA I have just added using the pool calculator, or lower levels not considering the stabilizer I added today?

 

[JasonLion]

The rule of thumb for CYA additions is to behave as if you hadn't added CYA for 24 hours, then switch to assuming the CYA level as already reached your target CYA level after than.

It is easier to lower TA first, then add borates, but it works either way. You didn't mention it, but if adding borax to raise your borate level, I assume you are adding acid also to keep the PH stable?

 

[Amy.M]

The bottom section of the pool calculator shows that the CYA going in right now will decrease the pH by about 1.2. I was thinking of matching that change with the appropriate amount of borax. But, that would also raise the TA, hence my hesitation. Last year, I was able to add borax to offset the pH changes of adding other chemicals, but my TA was always low so it wasn't a concern. Is this not a good way to do things? I've gotten into the habit of trying to add as little stuff as possible, is this a case where going all in at once is better?

 

[JasonLion]

CYA will lower both PH and TA, borax will raise both PH and TA. If you add amounts of each such that the PH comes out even, the TA will only go up a small amount.

Also, that is adding borax to raise the PH, not adding borax to raise borates (which takes twenty or thirty boxes of borax, way more than you will will be using for this).

Don't try to raise the PH in anticipation of the CYA lowering the PH. Test the PH and adjust as needed. CYA dissolves slowly, borax dissolve quickly, adding at the same time is not a good match.

 

[Amy.M]

For my little pool (using pool math) it would take less than four boxes of borax to raise borate from zero to 50ppm. It takes about half a box to change my pH by 0.5, an adjustment I had to make weekly in the past. I normally wait 24 hours between additions (excepting CYA), and test for actual changes before countering with another chemical. Do you think 24 hours after the stabilizer granules have dissolved is sufficient? I obviously don't have a very good feel for anything CYA related; I only learned that I needed it in August of last year and added it once.

- - - Updated - - -

There's also the possibility that I have not been using the pool calculator correctly, in which case, I'm doomed.

 

[JasonLion]

Sorry, I missed that your pool is small. Still that means that the amount of borax needed to adjust the PH goes down as well, so it is still way too little to have any significant effect on your borate level.

You should be testing the PH daily anyway, which is frequently enough to deal with any changes resulting from the CYA addition.

 

[Amy.M]

I will continue testing every evening. I will surely be back after the CYA dissolves to check with you pool veterans before making changes. Thanks so much for sharing your expertise and time!

 

[Amy.M]

I finally did my first CYA test using the T-100. Here are the results from today's testing. pH 7.5, TA 110, CYA 70, FC 5, CC 0. The water is sparkling and perfect. I have decided to not worry about adding borates for now. Things have been stable for the past week, so I am going to go for the "less is more" approach and leave well enough alone. Any reason why I shouldn't add salt today so we can start using the SWG?

 

[Abigail K]

I assume you've been testing your FC and CC with the TF-100 kit?
If so, and since you mentioned things have been stable, you could jump right in.

Hold diamond day (post #5).

 

[Amy.M]

Thanks. Richard suggested the same thing a week or so ago when I started filling. I would never have thought kids could have so much fun with a few giant bags of salt. I added it last night and had my son "help". Even manged to get a decent science discussion out of it regarding heat and agitation and how they relate to dissolving solutes. He had a great time with it.