Need a Little Help...Possible Deficiency

[shinedog]

I have a plant that for all practical purposes has been extremely healthy. It was placed into flowering on 5/5 and has started developing buds. Today hoever the plant seems to be having some problems with leaves curling in all directions and brown spots and actual brown areas on some of the leaves. From what I can tell the leaves toward the top seem to be the only ones curling, but the leaves below and kind of curling under like a claw and have little brown spots. I would describe it almost like little rust spots.

I have attached some photos for review. Unfortunately, these were taken in the flowering room and everything has a yellow tint to it. As for other details:

1. The plant is from a clone that had no issues.
2. It is being grown in soil (Fox Farms Ocean Forest).
3. It's in a 5 gal container.
4. It receives half strength Fox Farm nutes every 3rd watering (so about every other week)
5. It is wa.tered with PH balanced water at 6.5ph (usually every 3 days).
6. it is flowering in a room with 2 600w HPS lights about 31/2 feet above the plant.
7. Humidity levels are between 30% and 40%. Temps range from 65 to 80.

Any thoughts on what this could be from is greatly appreciated. I've never really had a defeciency before so your thoughts are welcome.