Yeah he states, that's it's not like soil, but not like hydro so the optimal ph is 6.2-6.4 is what seems to think seem best with promix, since I think he says it's soilless that's why he uses aluminum sulfate I think is what he said to maintain the ph at that level. He also has a great recipe with it, adding things such as ewc,blood meal, bone meal. To make a more full mix, where he states that with that mix, only 1/4 strength nutes are needle throughout.