smoke24answered grow question 4 years ago If growing in soil ph should be 6.5-6.8. If growing soiless ph 6.2-6.3. If you check runoff ph you will be able to get an idea of what to set your feed ph to, in order to get your ph in check. If your ph is good, then you can add cal-mag to your feedings if you aren't already, about 1tsp per gallon. Hope this helps. Happy growing.