I've grown this pheno twice before and it never got like this. I previously used crappy generic lights and Plagron Cocos AB or Plagron Hydro AB. I've switched to Canna Coco and recently upgraded to 301h EVOs. 

I've switched nutrients early during the grow. Even before I've switched lights, there was something going on that seemed like mild magnesium deficiency that appear in the top of the canopy (not necessarily new growth or old growth) with some tip bleaching. I thought it must be the excess light paired with under-watering, because they were growing too close into my old lights and the autopots weren't turned on yet.

New light seems to have made it worse, even though I run it at 70% power, which is less than 500W in a 120x120cm/4x4ft and 30-40cm/12-16in above the canopy.

I don't do any pH adjusting, it naturally comes out to 5.5-5.6. But I've noticed it drifts very little, and rarely goes above 5.7. Could that be the problem? Re-calibrated my meter just to be sure and it was accurate. 

  
Plants are now in Autopots but I've been top watering until recently. I use soft water (40ppm). I don't use extra cal-mag except when I added epsom salt. I use 4ml/l of Coco AB (which comes out to around 2.0 EC) and calculated elemental calcium to be 212mg, and magnesium 68mg, which should be more than enough.

Temperatures and humidity are decent, 26-27C/79-80F and 60-65%. I run airdomes.

  


Switched lights and nutrients and plants look awful