I hate to respond a question with a question. Are you eating it fresh or are you canning it? We're talking about botulism and making your salsa acidic enough to make sure your range is lower than the shelf life of that terror.
If you're eating your salsa fresh you don't have to worry about pH. Go by taste for about a week of shelf life.
If you want to freeze your salsa you won't have to worry about pH for about 2-6 mo.
If you are legitimate canning your salsa I believe you need to do whatever it takes to make your salsa acidic enough to avoid the plague. 4.5 pH? Lemon juice, lime juice, apple cider vinegar, and citric acid are added to drop the pH of your canned salsa. Test it on the way in. Test it on the way out with pH strips to make sure you're acidic enough. Also, adjust to taste.