COCO COIR Baby plant problems

[SilverIceCat]

Hi.
Im currently starting my second grow and seem to be having issues. I'm growing in a coco coir/perlite mix under a 400w HID lamp. I've just recently transferred my 3 week old seedling into a bigger pot and the seem to be dying. The leave are tuning like a grey color and becoming very brittle and crumbling. I gave them a water with a very diluted amount of cal/mag and cannacoco a and b before the transplant. So not sure if that has caused it. Is there anything I can do to save them.
😣😭 TIA

 

[Campesino]

Fairly certain that is Cal deficiency from un-buffered coco.
I would buffer additional coco and re-transplant. The alternative would be to give them heavier doses of Cal Mag, but you will be releasing a lot of K and running ECs that are too high.
The plant is not the problem. it is just losing the competition for Cal to the Coco. Check out my Coco guide in my signature - feel free to ask questions