As I reported in this thread: Planning for RO treatment I had the Reverse Osmosis process run on my pool run back in late October.
After re-balancing the chemistry the CH was 200-225 (Test the same day gave 225 two subsequent tests about a week later gave 200). Now 2 months later the CH is 325.
The auto-fill has been turned off. The only fill water to replace the small amount of evaporation has been rain water, so the only source for additional calcium I can think of would be from the now roughly 14-month old plaster. Is that possible?
The pool has an auto-cover and is normally covered, the total evaporation loss since October is something well under an inch. After a rain (which surprisingly we've been getting this year) I pump off the cover into the skimmer with the filter running to replenish the pool before sending the rest to the storm drain.
As noted in the thread linked above I also added 50 ppm borates to the pool after the RO treatment. And that has indeed helped to stabilize the pH rise, I now am adding acid weekly, vs twice a week before. But I think part of the gain is that with the reduced CH level I can allow the pH to rise to 8.2 before adding acid, and still have the CSI in range (less than 0.3). The weekly additions of HCl are the only chemical additions made in the period after the initial re-balancing.
After re-balancing the chemistry the CH was 200-225 (Test the same day gave 225 two subsequent tests about a week later gave 200). Now 2 months later the CH is 325.
The auto-fill has been turned off. The only fill water to replace the small amount of evaporation has been rain water, so the only source for additional calcium I can think of would be from the now roughly 14-month old plaster. Is that possible?
The pool has an auto-cover and is normally covered, the total evaporation loss since October is something well under an inch. After a rain (which surprisingly we've been getting this year) I pump off the cover into the skimmer with the filter running to replenish the pool before sending the rest to the storm drain.
As noted in the thread linked above I also added 50 ppm borates to the pool after the RO treatment. And that has indeed helped to stabilize the pH rise, I now am adding acid weekly, vs twice a week before. But I think part of the gain is that with the reduced CH level I can allow the pH to rise to 8.2 before adding acid, and still have the CSI in range (less than 0.3). The weekly additions of HCl are the only chemical additions made in the period after the initial re-balancing.
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