ph range for marijuana grown in pro mix bx (soiless mix)

Hi. I have a general question about pro mix bx. I just started back growing indoors. Ive been growing in pro mix bx, (soiless medium) for years. i think i,ve had fair, to good results over the years, but i know theres room for improvement, (my ph range.) I've heard ALL kinds of ph ranges to have when growing marijuana in pro mix bx. Dose anyone have any answeres, or suggestions, i would be most greatful. Thanks.

ph for hydro and coco is about 5.6 to 6.2
promix should be about 6.5 to 7.0
outside dirt about 6.8

I've been using pro mix for yrs also,and i think it's the best medium ,it's easy to keep your plants growing ,i've aslso tried hydro ,but came back to the pro mix,i keep my PH at6.2 works great!