buzz62
Well-Known Member
My new TDS/EC meter has two settings for ec (µ or mS), and either ppm.5 or ppm.7. The ppm.7 reading reads a lot higher, ppm.5 =1000 ppm tds vs ppm.7=1350 ppm tds in my Advanced Nutrient solution at the 4 ml/L rate. It's EC is 1.9 mS. I had read somewhere that AN uses ppm .7 for their baseline, but this scale is totally new to me. Should one assume that most of the ppm readings one sees on this site are in the lower reading ppm.5, which is what my first ppm pen is in? Reading Ed Rosenthals handbook it appears he is using the .5 ppm scale as he states "to be wary of nutrient solutions stronger than 1200 ppm or EC 2.4 mS", and he does discuss the ppm.7 a little, but does not reference which one he is using elsewhere! I gotta say, seeing the higher reading scares the heck out of me!!