this is a hydro grow btw.

"Hydroponics is a subset of hydroculture and is a method of growing plants using mineral nutrient solutions, in water, without soil."

It make look like dirt to the average person but its not. It contains no nutrients for the plant to absorb. With my experience with sunshine mix, I would aim for a good 6.0-6.5 when it comes to ph. This allows the mycorhizzae to colonize and help your plant absorb nutrients. If you drop the ph too low you kill off those wonderful benies and render them useless.