New Setup: Borax, SWG, Overall Balance

[catnip]

I've just completed my initial setup of a SWG system with Borax and would appreciate feedback on the current measurements and any recommended changes:

FC = 5 (am still adjusting but plan to keep around 5 ppm because of unpredictable heavy bather loads.)
CC = 0
pH = 7.7
CA = 100 (TA corrected for CYA)
CH = 340
CYA = 65 (planning to ease this up to 70)
Borates = 45 (as best as I can read the test strips)
NaCl = 3200 ppm
Temp = 85

According to ChemGeek's spreadsheet, the Calcite Saturation Index comes out at 0.00. Is this too good to be true, or am I missing something that needs to be adjusted? Also, I've read some discussion between ChemGeek and Waterbear about some advantages to moving CA a bit lower. Any thoughts on that?

Thanks for all the work you pioneers have done and reported here and on the Pool Forum!!

 

[Poolsean]

Keep an eye on your chlorine level and adjust the output of the Pool Pilot so as to maintain a steady FC residual.
The rest of your chems look fantastic!
Thanks for selecting Pool Pilot.

 

[Guest]

Lowering your corrected alkalinity (I assume this is what you meant by CA although it is usually referred to as corrected TA) might help you achieve better pH stability and less acid useage. If you are going to do this don't bother with the correction and just lower the uncorrected TA to about 80 ppm. Since your calcium is at 340 ppm you might even try going as low as 70 ppm. Don't worry too much about the saturation index. It really is only a rough guide for pools since it was developed for closed systems. It can give you a rough indication of scaling properites but it has been found fairly useless in predicting corrosivenss. The main variable in the forumla for the SI that has the greatest impact on scaling is the pH so if you keep that from climbing you should not have any problems.

Borates are fine. The strips are not the easest thing to read but if you are in the 30-50 ppm range they will do the job.

 

[catnip]

Waterbear, thanks for the feedback on alkalinity; I hoped you might chime in on this. I got the CA (carbonate alkalinity) nomenclature from Ben's Step-by-Step Guide to lowering alkalinity. I presumed that it's the same as corrected TA. If I take TA down to 80 that would equate to a corrected TA of about 55. That seems quite low, but I'll trust you and ChemGeek if you say it's OK. And I would like the benefit of improved pH stability and lower acid usage.

Is the Bleach Calc pH calculator valid/accurate for the amount of acid required to go from my current pH of 7.7 to 7.0? And I presume I should follow Ben's guide which says to lower the pH in steps, not all at once.

 

[Guest]

carbonate alkalinity is actually usually abbreviated kH which stands for carbonte hardness (it's actually a German abbreviation) and has nothing to do with water hardness. Carbonate alkalinity would be your uncorrected alkalinity since it is referring to the alkalinity from the carbonates and the bicarbonates in the water and not from other sources such as isocyanurates (from your CYA) or borates.