CSI pointing to 100+ TA

[revnelson]

Hello all, first I want to say thank you for the huge amount of knowledge and help I've received here already.

I'm currently dialing in my 15,000 gallon plaster pool after installing a SWG, draining due to CYA levels over 200 from previous owner, and refilling. My fill water tests as:
pH 8.2
TA 120
CH 125
Salt 600

After adding a bit too much salt, 8lbs of Calcium Chloride, and ratcheting the TA down via MA and aeration, my current levels are:
pH 7.6
FC 6
CC 0
TA 90
CYA 70
CH 250
Salt 4400
Borates 0
Temp 76

I'm still working to get CH up to 500. I live in Phoenix, AZ where we have little rain, high evaporation, and frequent top-ups. Since the fill water already has 125 CH, would you agree that 500 is a good target?

I'm also planning to add Borates to 50ppm tomorrow. In the Why and How thread, it says to "adjust your TA level toward the low end of the appropriate range for your pool type". It then links to a recommended levels chart that doesn't exist any longer. Going by the PoolMath app, this would be in the 50-60 range.

I don't mind doing the MA and aeration dance a few more times to get there, but playing with various levels of each chemical in the CSI page of the PoolMath app make it seem like my TA should be 100+. This is a great deal higher than all the TA recommendations I've seen around here and in the PoolMath app, so I wanted to get a sanity check and see if that's normal or if I'm missing something else before proceeding.

With the levels above, the CSI is calculated at -0.36. Changing the CH to my target of 500 and entering 50 for Borates (leaving TA at 90) raises the CSI to -0.11. If 500 is agreeable for CH, all the chemicals seem to be in good range and the only one I'd prefer to play with is TA. To get my CSI to 0, I need to enter 109 for TA.

TLDR: Does CH 500 and TA 110 sound reasonable?

 

[ajw22]

What is the CH and TA of your makeup water?

With high evaporation you will be adding CH with your makeup water. Your CH will rise naturally. Do not raise your CH artificially or you will be hitting high CH limits much sooner.

You can work to lower your TA but with high TA water it is a losing battle. Your TA will not stay down.

Start with your CH at 200 maximum. Maintain your pH in the 7’s and let your TA land wherever it wants.

 

[proavia]

In PHX, a CH of 250 is fine. It will increase on its own by 1 to 1.5 times your fill water CH in a year.
TA of 70-ish will slow your pH rise.
Let the pH sit around 7.8 - 8.0 and your CSI will be in the 0.00 to -0.30 range, given your other current parameters. You want CSI slightly negative to minimize scaling in the SWG.

Be sure to take the CH and TA tests to their end point.
Continue adding drops until the last drop no longer changes the color - and then subtract that last drop from the total.

Wait as least a year before considering Borates - get to know your pool first.
You need to get the TA lower before adding Borates.

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