Not sure where you got that info. Did you look at the post I sent you with all the charts ? There's a sweet spot between 5.8 - 6.0 that gives them everything they need. 5.8 is the best from my interpretation so I try to keep it there. The only time I vary my pH going in is if I see my run off come out 5.5 pH or less. In a case like that I'd up it to 6.0 - 6.1 for a couple of feedings & bring it back to my desired 5.8. My boundries for pH going in are 5.7 - 6.0. Nothing higher or lower.