I'm also using MegaCrop 1-part in coco/perlite, but mine stayed green, with no extra CalMag or other supplements. I'm following the feed schedule at GreenLeafNutrients, but dosing a little less than their recommendation. I started out at 1.5 g/GL as a seedling (grams per gallon). By day 21 I was dosing at 3.5 g/GL. The vendor feed schedule recommends finishing at 6 g/GL, but my last grow I stopped increasing at 5 g/GL, around day 50, and added 1 g/GL of kelp extract from then to the end. I liked the results, so I plan to do that again. Somebody said photos are hungrier than autos? Maybe the extra CalMag was locking out Nitrogen? It's all voodoo to me, which is why I stick close to the vendor recommendations.