leaves curling up and discoloring

hey, yesterday morning i checked my plant in the morning i saw the oldest leaves were curling upwards, and there was some discoloration. i have done some research and i believe it looks like a magnesium deficiency. i was wondering if anyone else believes it is a magnesium deficiency before i put 1/2 teaspoon/gallon epsom salt in my water.

http://img46.imageshack.us/i/dscf8479.jpg/
http://img96.imageshack.us/i/dscf8481.jpg/

whats ur temps at in room. but yea it does look like a nute deficiency. mine started to do that but i hit em with some guano tea and they be doing ok now.

right now its at 77 degrees, the hottest it gets is 85 degrees, and the coldest it gets is 60 degrees

i just put 1/2 tablespoon/gallon for spraying on the leaves and 1 tablespoon/gallon for the soil of epsom bath salt. it is ready to go, should i do it?