Quote Originally Posted by greenatik
not saying you're wrong about it being a magnesium deficiency. but what are you growing in and why would you need to add calmag? are you running distilled/osmosis? i've never had spotting like that with mag deficiency and I run into it all the time in coco with osmosis...
For what it's worth, I have had the spots show up with a mag deficiency. The discoloring of the leaf edges shows up first, then, as much as a week later, the spots show up about the same time as the discolored edges take on a rust color.