What are these brown spots on leaves!!

[dougefresh]

-indoor
-hydroponic
-hyrdroton rocks and rockwool in a hydro system
-Tap water
-6.7 PH
-4 weeks old
-mother earth supertea from advanced nutrients (full dose every week)
- 400w MH 1 foot abovr plants
-78 degrees durting light and not sure during dark
-38% humitiy
-18/6 light schedule

Help please, my plants are growing brown spots and are reeally turning yellow does anyone know what wrong. Is is calcium deficiency and nutrient burn ??

dougefresh Reviewed by dougefresh on 02-14-2008. What are these brown spots on leaves!! -indoor -hydroponic -hyrdroton rocks and rockwool in a hydro system -Tap water -6.7 PH -4 weeks old -mother earth supertea from advanced nutrients (full dose every week) - 400w MH 1 foot abovr plants -78 degrees durting light and not sure during dark -38% humitiy Rating: 5