Nitrogen deficiency maybe? Please help.

I am just starting my fourth week of veg. I have been using roots organic soil. I also use fox farms entire nute lineup. I have been feeding every other watering. Watering every 2-3 days. I have them under a 1000w hps lamp, about 2 feet away.

I just recently noticed that some of the leaves in the middle of the plants are turning yellow. I think it might be a nitrogen deficiency. What do you guys think?

Also do you guys think these look small for being three weeks old? They are only 8-10 inches. The nodes are very close together. I started them from clones in 2 gallon pots. The strain is purple cream. I also have hindu kush and bubba kush. They are much taller, around 14-16 inches.
 

Attachments

Top