According to Wikipedia, there are three pronunciations of pH:
- An older pronunciation from German, ペーハー.
- A newer pronunciation from English, ピーエイチ.
- A variant on the latter, ピーエッチ.
It seems like these are all still in use, but the long-term trend is toward the English-derived reading. According to Wikipedia, ピーエイチ was decided upon as a standard reading by JIS in 1957, and this was revised to ピーエッチ by JIS in 1984, so you may wish to follow the standard and read it ピーエッチ.
As for the numbers, we have a question about how to read a range of numbers already. In short, I think you can read the numbers like you normally would, pronouncing the
〜 between them as から, or very formally as ないし. I don't think you need to add a suffix.