Leaves starting to discolor and seems to be spreading.

So Ive got a sweet tooth growin out and it seems to be having some issues :

http://imageshack.us/photo/myimages/401/20111217112404649.jpg/

It starts on the bottom leaves and has slowly transferred to most of the other leaves... Now I have a GDP that we are also growing out and it seems to be spreading to that.

Is this a fungus type issue, or just deficiency and its coincidental my GDP's are doin the same thing?

Ill post up another picture of the backside of the leaf shortly...

TIA.

heres the backside as well :


http://imageshack.us/photo/my-images/862/20111217112413242.jpg/

TTT. Anyone have any ideas? Is it just a deficiency?

My best guess is calcium deficiency, which can be solved with cal-mag. Do you pH your water and such? The problem may be the soil is too alkaline or it's being locked out. Hopefully others have input because I'm curious to see what it is if I'm wrong!

Here's more info for diagnosis if you want to take a look: http://www.420magazine.com/forums/problems-pests-disease-control/81275-cannabis-plant-pest-problem-solver-pictorial.html