The runoff from the root chamber of my aero system measures 3.6 on my bluelab truncheon. This is the highest reading on the bluelab and I suspect that the actual EC is even higher. I mix my nutrient res at EC 1.6 and PH of 5.5 so that is the strength when it enters the chamber. The PH of the runoff stays the same at 5.5 but the EC goes sky high. I wonder what the hell is going on in there to change the EC from 1.6 to more than 3.6. Can anyone shed light on this subject?