The egg and grapefruit diet doesn't involve you only eating eggs and grapefruits for days on end. While that might cause you to lose weight and fast, it is not a healthy way of doing it and it doesn't include all the nutrients your body needs daily.
Yogurt contains lactobacillus, a good bacteria that helps fight bad bacteria in your intestines and vagina and helps your vagina stay in the optimal pH range. Eating yogurt regularly can prevent your vagina from becoming too basic, but it can also be used topically to cure a yeast infection or BV.
Adjust pH by adding PH Up or PH Down solution. Your goal is to get your water in the right pH range for your growing medium. If your pH is too low, you need to add PH Up, and if your pH is too high, you need to add PH Down in order to correct the pH. Re-test to make sure pH is in proper range.