New Growth is yellowish

Sprouted 3/5/12 so we are in the 4th week of veg. About 1 week ago or so I had put nutes in and curled some of the leaves so I changed my res and put plain water back in it, things fixed themselves but now the new growth is coming in yellow. So I'm guessing this is an obvious sign of a deficiency, nitrogen? I put nutes in it yesterday when I first noticed the yellow, it's at about 250 PPM right now. Should i keep it at that judging by the pictures? Should I add more? Just a little skeemish because of what I did to the leaves before with the curling... First pic is of the entire plant so you can see the general size, second pic is of the yellow growth.


Forgot to mention, 5 gallon DWC bucket, water is about 1-2 inches below netty pots, 6 CFL lights, PH is at a steady 5.8 and water temps range between 70-73 degrees, using Fox Farm Big Grow nutes. Let me know if any more info is needed.
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If you are just adding nutes back in, yes, they will be all good. You can see the tip burn starting, then you flushed the plant and stripped it of the nutes, building back up is a good idea.. at 4 weeks you should be at only about 1/2 strength nutes anyway.. you're going 1/4 by the sound of it. Next time you top up your res, use 1/2 strength veg nutes as the top up water.. then you should be good to run full strength after a week of the 1/2 strength, and be back on track. Good job catching it before there was too much damage done.