Nute burn? Nitrogen Def?

[Thunderfingers]

Bagseed grown under 2 75w CFL's. Plants have been doing great for a first time experiment but one of the plants seems to be headed south. I've been using a 20-20-20 mixture once a week. i switched to plain water a week and a half ago and havent seen much improvement except in the very top of the plant. I switched to a 12/12 cycle about 3 days ago. Any suggestions? Should I flush the plant?

[Cyclonite]

When in doubt flush it out....looks like your N is not low at all. There is some sort of problem though, I think that looks like a zinc deficiency. Flush with PHed water and feed with a balanced nutrient. I use hydro nutes added to PH water for my soil ones. Make sure all the plants needs are addressed.

[Thunderfingers]

thanks very much for the reply. Can you elaborate on the "well balanced nutrient part"? I'm a noob in the worst way!