Cob_nUt
"Justa Ganja Lover"
Your meter may be fine Mac. Different manufacturers or regions have different number for ec readings at the same scale.Ok so maybe I need a new meter. I don't check ppm too much, I have a handful of feeds that I use for different sets of plants. And I've used them for quite a while. It's probably been 6 weeks since I used my pen. I'll be ordering a new pen today, lol. I came up with.....
105-tap
Add 4 grams mc = 403
1 gram SC = 458
+2ml calmag = 515 for the solution.
515ppm seems low to me, so it's gotta be my pen.
Blue Lab 0.1 EC PPM 50
Hanna " " " 50 USA
Eutech 64 European
Truncheon. 70 Australian.