pH is a critical measurement with our nutrient solutions, measuring the concentration of hydrogen ions. The higher the concentration, the more acidic the solution - the lower the concentration, the more alkaline the solution. pH scales are logarithmic! This means that an increase or decrease of a single integer value changes the concentration by tenfold!
It is crucial that we understand this. Moving a single point can have dire consequences to our plants as the concentration of hydrogen ions varies greatly with that single point. pH adjusters may be needed to accomplish the correct pH for your solution pending on your media and cultivar.