I've used 60% all mix 40% light mix soil...i've noticed that once i started giving them enough water to get some run off...it's ppm is around 2100ppm 4.2 EC
isn't it too high? how can i Lower it?
Yea, that's way too high. Feed double the normal amount next time with just water, no nutes. If you have access to distilled or RO water it will bring it down a little quicker.
Your EC really shouldn't exceed 2.0 in most cases.