Lower limit of TA for "happy place"

[Fuldo]

Just got back to my Florida pool after being away for a while including a time with much rain and many drainings by a relative. A few things had drifted and I noticed that my PH was only 7.5 and the pool hasn't had an acid addition in a long time., in fact nothing acidic has been added including pucks. I found the TA at 40, lower than it's ever been. FC was 6.5, PH was 7.5, TA was 40, CH was 225, CYA was low (less than 30) and salt was 3600 with a water temp of 81 that calculates out to CSI of -0.72. I bumped the TA up to 80 (goal was 70), CH up to 250 and the CYA up to 50 (a good point for this enclosed pool).

My question is: did I overreact in bumping the TA up? Is TA=40 reasonable if the PH seems stable and doesn't drift-up and the CSI is in range? After adding the baking soda to raise the TA I ended-up adding acid to drop the PH back after it immediately rose to about 7.9

 

[ajw22]

Depends what the pH and TA is of your fill water.

I might have watched the pH and TA daily for a while and seen if it self corrected.

 

[Fuldo]

Unfortunately this a a second home, I come and go and I was away for 2 months this last stretch with a relative monitoring the pool. Daily monitoring isn't possible, I'm lucky to get weekly FC and PH readings in the summer when I'm mostly away. The only water added to this pool the last few months has been rain water so city water conditions aren't much of a factor and the city water is rather PH neutral (about 7.0). Under similar conditions over the last year or so with TA typically 50-70 the PH tended to rise slowly and required bi-weekly additions of MA. This is the first time I've found the PH so low without any acid added for a month or so.