Measuring pH of RO
water is useless if you're nearing 0ppm TDS
. You can use the same test kit on the same sample and get two different readings with "pure" water. In theory, the pH of "pure" water should be 7.0 (neutral). But it won't be, or if it is... it's purely luck. The ratio of free ions in the water is so low, any little contamination from anything can throw off the results. Pretty sure your source water isn't the problem.
My guess is its your 2-part dosing. I'm not familiar with the Kent 2-part, but I don't believe any 2-part solutions will "balance" your pH for you. If you add too much of the alkalinity - or if your tank isn't using it, as is probably your case - then you're probably going to see an increase in pH once your levels get out of whack. Do you have a alkalinity test kit? How 'bout a calcium test kit? Those are the two elements you're adding with the 2-part solution, so I'd be sure I was testing for them to see where you're at.
Until you get a large amount of coraline algae, dosing a 2-part solution isn't doing you any good and is most likely messing up your water parameters. Weekly water changes will give you what you need until the growth of coralline (and coral, eventually) strips more calcium out of the water then you can put back in with a water change. And testing is the way to keep track of that.
Here's a good article...
Calcium and Alkalinity by Randy Holmes-Farley - Reefkeeping.com
And here's the article to go to when you get your calcium and alkalinity levels all out of whack...