same thing, that's why i'm asking. two of my gals had their tops turn lime-green/yellowish...i thought it was a cal-mag deficiency at first but that wouldn't make sense (two others are fine and the last two feedings were plain water)... i'm thinking it was the cooltube creating hotspots and bleaching my plants from too much lumen intensity. my cooltube was like 3-4 inches off the top and my hand felt fine underneath so it can't be heat. now they are 6-7 inches off the tops and i'm hoping the new growth will be normal green.I just made a cool tube a few days ago. I made the mistake of putting some plants too close. I can put the back of my hand against the glass but it still bleached out the closest leaves.