All i know is i didnt take care of the PH, PPM or temperature properly and my plants are just coming out of a 2 week nutrient lock.
The digital ph is awesome, i can get it to exactly the number i want.
The PPM meter is also invaluable because even though I measured the nutrients out to the gallons of water, my tap had 150 ppm per gallon and i ended up with over 1000 too much ppm. So i burnt some of the leaves, the first set in fact.
Everything is a factor when your growing this stuff, im learning so much that even if this crop fails, i wont be upset. I will try again and again.