pH?
Growers argue about PH, mostly because it is diferent for SOUIL from HYDRO and visa versa. I own 14 books on growing pot, and only two are old ones. Of the 12 newer ones, they all saying different percents, that vary from 5.8 to 6.5 for Hydro. When my pH creeps up to 7.0 overnight, I do not get NUTRITIONAL LOCKOUT. At 7.2, I DO get LOCKOUT. That knowledge came from experience, my own personal experience. I use a pH meter now. I grew for 3 years with test strips.
I like anything between 5.8 and 6.5, that works best for me. If you use the color strips, you can not be as accurate but you can test them cheaper. You can get a good pH meter for $59, but the test strips work fine.
and some good advise FOR YOU, if you arE just starting, 2 THINGS.
1, DO NOT TELL, DO NOT TRUST A GIRLFRIEND! THAT IS HOW YOU GET CAUGHT AND BUSTED.
2, SPRAY A PESTICIDE like HOMEGUARD in the floor and corners in your closet or grow room! Those pesty spider mites will find your GROW if you don't spray first.