nicksanswered grow question 4 years ago keep in mind that PPM/EC meter can lose their calibration, I run promix and monitor my PPM/EC and if its much higher than I put in I lessen the amount in the feed, but this is my first time so take it for what it is. I just wanted to mention the calibration thing, because i have 3 meters, only one is correct you can get calibration fluid online, fairly cheap i paid $10 for a small bottle of 1000PPM, my one meter tested within 1 pt, so i know its good, the other read 600 and the other read 1500.
Also the error doesn't seem linear and the gap widens significantly the higher the PPM, for example the Good meter that reads 1000 the other read 1500 if the good one read 1400, the bad one could be as high as 4000ppm I couldn't make sense of it.
From the thumbnail above this text box, it looks like u might have one of the cheap meters i have i'd buy some calibration fluid just to have some peace of mind gl. Barring that you can strictly follow the guidelines for your feed, and adjust based on need and symptoms or you can use your meter as a rough estimate, and learn "the new scale its given you" GL you'll get through this