Apple fritter assistant

My af 30days old. currently inside my tent.
Under [Mars Hydro

4800 FC. At half power. 18” above canopy . Feeding has been 2-1. 1 ph water 2 same as first sometime they do a compost tea in the third with nutrients. Currently using pure blend pro at half the recommended. Every watering I give Humboldt secret tree trunk. At 2.5ml per gallon. To me, it appears as a nitrogen deficiency, but nothing I’ve tried is helping. out of five plants she’s the only one showing Like this. Am I going down the right path with nitrogen deficiency? Any any insight greatly appreciated