Deficiency problem

plant is 4 w old grown in coco/perlite under 160w cfl awaiting transfer,d master nutes 1/2 strenght ph 6.5

im no expert but I think your ph is off. high I think.i thought coco required lower ph than soil. I ph my soil to 6.5 - im not one to chime in on deficiency problems but I think I might be close to right on that theory. might want to research it..

Lower the pH in coco to that of hydroponic pH!

https://www.rollitup.org/index.php?threads/841773/

Yea it's the ph for sure. Get it closer to 6 some prefer 5.8. Mess around and do a 6 one time and 5.8 another, that way the mobile nutes are able to move better when you have a fluctuating ph within the range of your medium and nutrient line suggestions. It helps get magnesium up when you need or n or CA or iron, or even potash. It's good to know what likes what ph level so you can adjust accordingly and get the most out of your plants

Looks like a little n would help tho