Update:
Over the 4'th of July holiday weekend I decided to try an experiment at lowering TA. 8:30 AM July 3 I added 32 oz of 14% HCl and reduced the pH from 7.7 to 7.0, as checked a few minutes later allowing my swim current to mix the pool. There was no measurable change in TA. Poolmath predicted -10 ppm TA which is within the +/- 1 drop precision of the test so it's not terribly surprising there was no measured change. I then turned on my SPA spillover mode which runs the SPA jets at full blast generating lots of aeration closed the pool cover and left it run.
Checking the chemistry at 4PM the same day I found the PH had risen back to 7.6, TA still measured 60. Left the spillover mode running all night.
8:30 AM July 4 PH now measures 8.0, TA still 60. At this point I added another 32 oz of HCl, let it mix and checked the chemistry PH 7.2, TA 50. Left the spillover/aeration running.
4:30 PM July 4 PH 7.6, TA back to 60. At this point I shutdown the SPA spillover and went back to normal operation.
The one thing I learned from this experiment: 24 hrs of the SPA running causes as much pH rise as I would normally see in 4 days with normal usage (SPA running ~30 minutes/day). From this I conclude that the SPA usage is not a major factor the pH rise, maybe 10% of the total.
In the two weeks since the Holiday the TA has crept back up to 70 as I have been adding acid couple of times per week when the pH reaches 7.8 or higher. I have been slowly adding additional CYA as well with the intent to bring it up to 60 ppm.
Over the 4'th of July holiday weekend I decided to try an experiment at lowering TA. 8:30 AM July 3 I added 32 oz of 14% HCl and reduced the pH from 7.7 to 7.0, as checked a few minutes later allowing my swim current to mix the pool. There was no measurable change in TA. Poolmath predicted -10 ppm TA which is within the +/- 1 drop precision of the test so it's not terribly surprising there was no measured change. I then turned on my SPA spillover mode which runs the SPA jets at full blast generating lots of aeration closed the pool cover and left it run.
Checking the chemistry at 4PM the same day I found the PH had risen back to 7.6, TA still measured 60. Left the spillover mode running all night.
8:30 AM July 4 PH now measures 8.0, TA still 60. At this point I added another 32 oz of HCl, let it mix and checked the chemistry PH 7.2, TA 50. Left the spillover/aeration running.
4:30 PM July 4 PH 7.6, TA back to 60. At this point I shutdown the SPA spillover and went back to normal operation.
The one thing I learned from this experiment: 24 hrs of the SPA running causes as much pH rise as I would normally see in 4 days with normal usage (SPA running ~30 minutes/day). From this I conclude that the SPA usage is not a major factor the pH rise, maybe 10% of the total.
In the two weeks since the Holiday the TA has crept back up to 70 as I have been adding acid couple of times per week when the pH reaches 7.8 or higher. I have been slowly adding additional CYA as well with the intent to bring it up to 60 ppm.
