Please Help.... Yellowing Leaves

So the back story is that this little one is 25 days old from breaking groung. She is under 4 27 watt Cfl's 0n 24/7. Using a blend of Scotts Premium Potting Soil, Perlite, and Peet moss. Water only when its dry on the top half of soil (she's in a regular 6" pot) Haven't tested the ph, am watering with tap water put through a filtered pitcher, then left out to be at room temp. Started noticing the yellowing 6 days ago (pic1) now it worse. I've been reading a bunch on this board and im thinking magnesium or nitrogen deficency, i have not started using any nutriants yet. This is my first indoor grow and have only helped on a couple outdoor grows years ago, any help is greatly appreciated.

Well I found out Scott's pro mix is the same as miracle grow. They own Miracle grow and use the same ingredients. So you got the perlite, worm castings, peat moss and lime to balance PH. You would think that would be fine for a plant this size.

So, I would have to think ph is off and the plant is using stored nutrients instead of whats available.

what are temps. looks very much like heat stress. almost sure of it

you want 72-82. above 90, they slow drastically(yellow, drooping leaves) and die

the temps are pretty steady at 84-88. Have good airflow over lights and a fan providing air flow in the room. I am working on and exhaust system right now, I have a 400watt hps I'm going to use for flowering but don't have it set up yet.