This was my experience. I have had them on every grow I have had in the indoor tent with my Autopots and I never see any ill effects at all. I grow in coco/hydroton 60/40 combo, but I buffer the coco with cal-mag plus to help with those that issue, and I grow under led, so it is key. Trying to get to organic growing though. Just a little intimidated I guess. But the med cabinet is full and I can afford to screw it up a little, so I a man thinking the next grow might be when I try a switch.