Converting EC (electro-conductivity)to TDS (Total Disolved Solids). TDS = PPM. That is, TDS is measured in parts per million units. There are a lot of different conversion factors for this. This one is from the University of Minnesota Biology Department. The factor is as follows: For any EC reading .99 or below, multiply by 680 for TDS. For any EC reading 1.0 or above, use a factor of 700 for TDS. Note, this is for EC meters with a 1.0 scale. Some meters have a 10.0 scale, some a 100.0 scale, so do the appropriate math, i.e. for a 10.0 scale only multiply by 68 or 70, for a 100 point scale, mulitply by 6.8 or 7.0. To convert TDS to EC, just divide. (Edited by Herbsparky at 1:24 pm on July 14, 2003)
