If in fact the CYA is in a normal range say 30 then I can just take care of the TA as mentioned before.
Yes, just increase the TA to about 80 to 100, which will correct the TA and pH.
However, you need to monitor the TA and pH as you use tabs because the tabs are acidic.
50 lbs of trichlor in a 25,000 gallon pool will:
Raise fc by 219 ppm
Raise CYA by 133 ppm
Raise salt by 179 ppm
Lower TA by 154 ppm
To raise TA by 154 ppm, you need 63 lb of baking soda.
So, you need 1.14 lb baking soda per lb of trichlor to offset the TA loss.
7 lb of trichlor requires 8 lb of baking soda to keep the TA constant.
In the above case with a CYA of 133 ppm, the CYA contributes about 133/3 = 44 ppm of the TA.
So, if the Carbonate Alkalinity started at 100 ppm the TA would also be 100 ppm.
However, at CYA = 133 ppm, the carbonate alkalinity will be 100 - 44 = 56 ppm.
To keep the carbonate alkalinity constant, you would need to end up with a TA of 144.
So, you need to add 154 + 44 = 198 ppm.
To raise TA by 198 ppm in 25,000 gallons, you need 73 lb of baking soda.
You need 1.46 lb baking soda per lb of trichlor to keep the carbonate alkalinity constant.
10 lbs of trichlor requires 11.4 lbs of baking soda to keep the Total Alkalinity constant.
10 lbs of trichlor requires 14.6 lbs of baking soda to keep the Carbonate Alkalinity constant.
