Someguy15 Well-Known Member Nov 22, 2009 #1 What is the preferred unit for concentration? EC? a lot of people seem to use ppm, but don't clarify if they mean .7 or .5 conversion factor.
What is the preferred unit for concentration? EC? a lot of people seem to use ppm, but don't clarify if they mean .7 or .5 conversion factor.
