i assume now you are ocd about the test sample water level and adding drops slowly
were you always very careful or a bit
"that's near enough" on the samples
not trying to point a finger, just looking for an easy answer to past discrepancies
So I’m a scientist by trade, albeit not a chemist. That said, I’m pretty precise with measuring. Sure I’m not using syringes to add water, maybe I'm not holding the tube 100% level, and maybe the meniscus is a bit above or below the line sometimes, but I’m pretty diligent. I rinse the tubes every time with the pool water and perform my dips at elbow deep (~18") always at the same spot in the pool (deep end that has plenty of movement from the deep end return). Fluctuations of 10, or even 20, pts doesn’t concern me as I understand there is an expected margin of error in these drop tests. But the incredible rise of pH, TA, and CH while I was away on vacation cannot be attributed to measurement error. And my constant rising of pH throughout the season...
I left for vacation on 9/11. On 9/10 this is where my numbers were:
- FC - 6.0
- pH - 7.3
- TA - 65
- CH - 430
- CYA - 80
- SALT - 3800
I returned on 9/19, so 10 days without human intervention, and my numbers were:
- FC - 3.0 (-3.0) - Explained by my reduction in pump run-time and SWCG output
- pH - 8.? (+ >= 1.0) - In my return test I estimated 8.4, I dosed with 1 gal and it reduced still above 8.0 so I assume it was actually higher.
- TA - 120 (+ 55) - ?? My TA has always been fairly stable at a range of 60-80. I expected to come up to high pH, but this was a big surprise. I don't believe this was a measuring error, validated by the 2 large acid doses that brought it back down to "normal" range (60-80).
- CH 490 (+ 60) - ?? Again, I cannot explain the rise in CH while away. Unless a neighbor came by and dumped 10lbs of CaCl in my pool it must have been extracted from the pool or scale. I last dosed CaCl on 7/29 which aligns with my measurements up until I left. However, once I left I cannot explain the rise in CH and TA.
If you look back through my historic log (+1 year) you'll see that I was a bit obnoxious with balancing the water (i.e. dosing acid at 7.8 just to get to 7.6, but even then it was infrequent because the pH was so stable. Take a look starting at 5/21/20 pH was at 7.3 (not sure why I dosed down so low be regardless)... pH remained the same all they way through 6/27/20 when I dose Borax to bring my TA up. But even then my pH remained stable at 7.6 through closing on 10/21/20. Another section to look at is 9/13/19-9/22/19. This was the same annual vacation we just took 2 weeks ago. I left with a pH of 7.8, dosed 32oz of dry acid, then returned 10 days later to a pH of 7.6. I would define this as stable.
I understand SWCG do raise pH, so I'll be dealing with acid more often than I did before. But my rise of an avg of ~.2 daily is, in my opinion excessive and really shouldn't be the case.
Please understand I'm not trying to argue with you. I understand this is a chemistry issue and not some weird anomaly where I'm being punished for past wrong doings. Just like you, I'm really trying to figure out what is going on so I can fix it. I'm 100% certain this is result of something I've done. I just need to figure out what that is so I can avoid it and get this Dang pool in some state of stability. This really has been the worst pool season I've had with this pool since we moved here in June 2013 and that includes 1 season of battling 2 instances of white water mold. The only thing different this year is SWCG. For next year I'm half tempted to disconnect it and go to liquid chlorine. I'll never go back to the tabs.
I appreciate all of your guys help. This forum is great, always has been. I appreciate
@JamesW taking the time to explore this with me.