Ok...what I'm hearing from this is that if I use an acidic sanitizer (like dichlor), it's OK to use Sodium Carbonate to increase the pH of my spa w/o raising the alkalinity? Or...what am I missing (not a chemist).
Here is the breakdown of what I'm using in my spa:
Currently I am using the TESPERT Pool and Spa Test Strips Hot Tub Test Strips but I've used several different brands before (including ones I got directly off the Softub Direct and the bottle my Softub guy gave me). How am I supposed to test it if not with these strips?
For sanitizer, I am using the Leisure Time Spa Chlorinating Granules (Sodium Dichloro-s-Triazinetrione Dihydrate) in conjunction with a Spa Frog mineral sanitizer insert which is a new-ish thing to help me not need so much chlorine. It seems to work.
I pretty much don't put anything else in it except pH Up (Currently it's Leisure Time brand too as the "Softub" brand was out at the time of purchase, but I seem to remember the chemical makeup is the same).
Don't seem to have a problem with alkalinity, though I notice cyanuric acid increases over time if I use too much chlorine.
Though, no matter what I have/haven't done, I've never been able to keep my pH high enough since we got our Spa last year. My Softub rep told me that the pH should be above the "ok" range on the strip to preserve the vinyl lining of the Softub.
Here is the list of things I bought last time I needed chemicals: