What is the difference between the Pro Mix Organic and the Pro Mix BX, I did a search for Pro Mix and only really saw people using the BX? They have the Pro Mix Organic on sale were I live at like $5 a 12lb/1cu ft bag. I plan on using the Pro Mix organic for a indoor grow, from clones to harvest? Do you need to add anything to the Pro Mix Organic, besides nutes during flour? I will be watering with PH corrected water.. Thanks,