Here's what I"ve learned over the last couple of monthat that I've owned my tub:
When I am first filling my tub, I find that getting the alkalinity correct is easier to do. It takes pH a while to stabilize so the readings are not accurate. When I first fill my tub using well water, the pH is 6.2 but over time, with movement and aeration, it rises to 8.3 (12 hrs). So, I initially check my alkalinity, which is about 230, lower the alkalinity according to directions and do not bother to check the pH. The next day my pH is about 7.2. Get the alkalinity right and the pH should eventually stabilize, it just takes a long time and lots of aeration for that pH to stabilize ALso, the strips are not very accurate and I would recommend a Taylor test kit.
If you are checking your pH frequently you will see that it fluctuates, especially after using the hot tub. Checking it and then trying to adjust it will cause you alot more fluctuation....you may see it too low, add pH increaser which will cause your alkalinity to go up, then later find your pH is too high. A vicious cycle. As I said, I like to go with the alkalinity reading when first setting up the tub. And after initial set up, I only check the alkalinity and pH in the mornings after the tub has been unused for many hours and run through a couple of filter cycles. I do this once a week instead of worrying about it daily.
