Yeah, I saw the other post about the acidity after I posted this.

I used to moniter with reagent paper, I got it from 911healthshop.com (took a lot of searching to find one that tests the right range). Pool stores have test kits, but the range was wrong. Then you just dip the paper in their pee, like testing for ketones. I remembered using it in science class in like 5th grade, so I knew they had to sell it somewhere. It is one of the things on the dipsticks that vets use to test pee, but those are expensive, and I found hard to get as a non-vet.
I had a kitty who had an internal cyst that caused acidic urine, that's why I was curious. It was pretty weird, and had to be surgically removed, and then his urine went back to normal. I caught it b/c his pee started to smell like vinegar.