i have never, not once ph'ed the soil.. what do will want to do though is ph the nutrient solution that you add to the soil, and keep it around 6.5 = 7.0...
any higher or lower and you simply add a few drops of either ph up or down to get it to the correct range.. be careful as a few drops of the down is really strong, as is the up, but it's a lil weaker than the down ime..