Yellow Brown spots on leaves, leaves curl inward, hydro setup

My second grow with the same setup. First grow went fine, but this time I'm growing 6 plants instead of 4. My question is, am I over feeding or underfeeding? I give the hydro setup a quarter cap of 7% nutes every couple weeks. I change the water completely at the same time. The leaves have small yellow spots that turn brown and then the leave curls inward\upward like a claw. Any ideas?




-indoor
-hydroponic
-Hydro system type (Wick\ebb n flow)
-Nutrients - Hydro 3 in 1 (the classic 7% of N, P, and K)
-Water pH - (6.5)
-Age of plant - 7 weeks
-Lighting source and distance from plant - Mercury vapor, 600 watts, 1 foot
-Temperature - 70 degrees, all the time
-% Relative humidity - 40%
-Lighting schedule - 24/0
-Type of ventilation your room has - (Windows, celing fan)

It sounds like Calcium deficiency, but I can't be certain with no pics .
What is your water source?
Pictures will help a LOT.

I don't know what hydro 3-1 is so can't comment on your nutes.....but your ph is too high....for hydro it should be lower....between 5.6-6.2. I would also lose the MV lighting...inefficient and hot.

Revised: The Complete Guide To Sick Plants,pH and Pest Troubles - PlanetGanja.com and that chlorinated city water you're using probably isn't helping (I'm assuming... if I'm wrong, sorry)