- Sep 18, 2024
- 6
- Pool Size
- 18000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Jandy Aquapure 700
History of my interest in this question:
Thank you.
- I found that after 6 months my salt cell was full of calcium deposits.
- After cleaning it I measured the Total Alkalinity (using TF-100) and found it to be 180
- Over the course of 3 weeks I added acid daily to keep pH at 7.2 until the TA was down to 70
- My understanding is that the pH in my pool rises every day due to aeration (there is a spillover from a raised spa and the lower pool.) I have been led to believe that this happens because there is an equilibrium between carbonic acid and dissolved carbon dioxide. As dissolved carbon dioxide is removed due to aeration this equilibrium drives carbonic acid levels lower thus raising the pH.
- The pH in my pool goes back down when I add hydrochloric acid.
- Somehow (I don't quite understand the chemistry details...) the lower pH reacted with the TA reducing it over time.
- General Pool Care: Now that I am "done" reducing the TA I am now maintaining my pool's pH at 7.8. Every 2-3 days after adjusting pH to 7.8 I measure it at 8.1/8.2 again. Does this mean that I am continuing to reduce the TA (though slower than I was at pH of 7.2) as a side effect of maintaining the ideal pH? Is this normal?
- Academic / Curiosity: If aeration raises pH by removing dissolved carbon dioxide and I lower pH by adding hydrochloric acid, then how does this not get out of control? I'm adding extra chloride ions and aeration is removing carbon dioxide. Won't I eventually run out of dissolved carbon dioxide / carbonic acid if there isn't anything replenishing them? Won't I eventually have a HUGE surplus of chloride ions unless there is some mechanism removing them? I'm sure I'm missing more elements of the chemistry at work here (presumably something to do with buffers?)
Thank you.
