Well, those cheaper skinny probes are not reliable in my experience,.. the A8 works on the same principle, but is more robust and better tuned,... but like I said, bad batches happen, and with no nutes going in, just Ca-Mg, then the soil itself, and/or pH is suspect... looking at that reading, it's too alkaline, opposite of what I'd expect honestly,....

symptoms don't match up with this either, lowers are fading/getting tapped out, new growth looks shaky; alkaline lockouts affect Fe and Zn first usually.... double check that Ca-Mg and make sure it's not gone bad, unlikely, buuuut,..... off color, smells weird, precipitates,... the fact that the Roots plants are OK points the finger more strongly at the

soil,.. are the Roots pots also mixed with Pro-Mix?