Sorry, I can't help you with pH levels, because I don't use this data. Nevertheless, I know it's especially important in Cheddar and Pasta Fillata cheeses. There is lot of discussion of this matter on the forum, so please run a search for this topic.
Although I am not experienced enough, I try to stay on the primitive side of cheese making like in those old days when pH meters were not available. As for you, if you intend to market your cheese, you should use equipment to ensure consistency and repeatability.