Deficiency

Are you Sure it is You Feeding your plant way too much, but we have nö Report. So we can Not further investigate, what are you be doing and what not.

to much nutes dude! flush it!

Zinc deficiency. Can be caused by high pH or excessive levels of phosphorous too. Can be addressed by the application via the roots of a dose or three of a quality, soluble trace mineral mix, which should be available from any decent garden centre. Judging by the colour of the leaves, you are feeding waaaay too much, (which may explain high P levels)......... leaves should be a healthy green, not almost purple/black! Without a diary and no ideas about what you may or may not be doing, it is impossible to be any more specific.

I think it could be Sulpher or Iron deficiency. Both have symptoms of top yellow growth. Make sure you ph and is dialed and you are not overdoing any other nutrient.