I kind of hate answering questions like this because a) No, I don't have a one paragraph answer (I had a website at one time to try to catalog what I have done and I moved it twice, because of the very ugly attacks on me -- it still exists but not much of it is published online) and b) the answers generally just fuel more ugly attacks.

For your first one: I didn't "test" anything. I followed progress symptomatically.

For your second one: I read up on alkaline foods and skewed my diet somewhat towards those (lettuce, white corn, and watermelon were a big part of my diet for a long time). I also took a lot of supplements ($300/month for years), some of which were alkaline minerals that people like me are typically deficient in (such as calcium and magnesium). I also found that excluding pro-inflammatory oils and certain other pro-inflammatory foods (like peanuts) made a big, big difference.

That's it in a nutshell, but, again, this is 13 years of work I am trying to summarize for you. So a nutshell doesn't really do it justice.

Edit: Sorry, I missed your third question: How it impacted my acidity. I no longer have acid reflux and similar. That's the best I can say about that specific question without being dismissed as a whack job. (I also have a lot less of other issues, but those issues are not things I can "prove" are related to reduced acidity.)