OK 1st thing you need to do is read all the FAQs if you havent already. Try to get a book its very helpful. OK the ph is tested in the soil if your growing soil, and tested in the water if your growing Hydro. Buy a PH tester the FAQs i think has the certain PH level chart during the different stages in growing the plant because it changes. Ferts can raise or lower PH levels but just test it and then go from there. Theres all different types of Ferts I use Sunleaves bat guano and Fox farm poducts like tiger bloom and big bloom.