Is this plant needing nutrients?

This is my first grow and has been going alright for the past 2 or so weeks. Yesterday it was looking fine, very green and alright looking. this morning I see the leaves curling up and down, turning slightly yellow, and one leaf is nearly all yellow with brown middle vein. The last time I watered it was 4 days ago. I just fed it again a little while ago. The first time I fed it a good amount of Fox farm big grow and after that it started to grow fine.

My plants about 3 weeks old, Blueberry strain, under a 600W HPS light (about 19'' away), Fox farm soil, 4 gallon pot, room temp is 77.

Since this is my first grow everything that happens to this plants looks new and suspicious. I've read around and think its probably a nitrogen deficiency and possible a few other nutrients deficiency. Big Grow has a bit of everything so would that help out my plant. Any help or advice would be great appreciate. Thanks in advance.

P.S. I'm really sorry about the crappy photos. it was the best my camera could take. I'm just trying to show the curling going all over the place.

My first thoughts is that the plant looks too young to be fed a "good amount of fox farm" I would have waited a bit more, not sure if this is part of the problem but a suggestion. Any idea on the pH lvl?
Good luck

harryhood said:

My first thoughts is that the plant looks too young to be fed a "good amount of fox farm" I would have waited a bit more, not sure if this is part of the problem but a suggestion. Any idea on the pH lvl?
Good luck

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The only reason why i added the nutrients was because it started turning completely yellow. The only thing it had been getting was light and water. I added a decent amount of the big grow and it got healthy green again until this morning. My pH reader broke and I haven't the time to get a new one yet. I've been using tap water that's been sitting around for 24 hrs if that helps at all.

Its burnt up quit giving it nutes.I know its hard not to you think ill feed it an itl grow faster! but it will actually do the opposite.dont feed it until it gets bigger the soil has everything that plant needs.you need to flush the soil and then wehen it dries out get back to watering with plain water for awhile.