You shouldn’t need to adjust the pH when you use the pH Perfect products, and you might do well to just ignore your pH readings to avoid concern. The product doesn’t actually (well, not much) change your pH as much as it makes the all nutrients and supplements available to the plant throughout a pH range of 4 to 8. So, unless you have some really bad water, you should be fine leaving it alone.
Note: pH will always change over time, even with plain water. This is why lots of people mix their nutrients right before they are ready to use them, rather than doing it early and letting them sit.
On a related note, I’ve found it best to use tap water and the Sensi products when working with soil, and reverse osmosis water when using the Sensi Coco products. I didn’t see where you mentioned what growing method/products you were using, so I thought I would mention both.
Unrelated, but important to mention because most people don’t realize this… when using the Sensi products, you should:
Add nutrient solution A to your water. Stir/shake and wait 5 minutes.
Add nutrient solution B. Stir/shake and wait 5 minutes.
At this point you can add all your supplements, but I personally like to add them individually in 3 minute intervals.