Need help, quick-stat! Total noob.

Hello there,
I'm having some problems as you can see. To give you as quick a run down as is possible; I'm growing Lowryder feminized autoflower in a stealth grow box with 2x 100w CFL red light (Lowryder autoflower skip veg state). I was unable to get any soil other than ericaceous soil, so I suspect that this could be causing the problem seeing as I've heard low PH's lock out magnesium and calcium. The plants are between 1 and a half and 2 weeks old, and are about 3 inches above the soil level, though the leaves are looking far more unhealthy than compared to when they surfaced. I have been watering them every 3 days with about 300ml each, until the soil was wet and dripping through to the tray below. I've had them on a 16 hour light cycle, 16 on, 8 off, which is meant to be optimal for low ryder. The lights are about 4 or 5 inches from the plant, and the stealth grow box is lined with mylar.
The things I think could be the problems are:
#1 I've already used a nutrient water mix on them, could I have used them too soon?
#2 Calcium/magenisum being locked out as result of low PH.
#3 Overwatering (maybe?) though the tray below had an awful lot of water in it
#4 underwatering? I don't think so as the plants weren't dry to the touch.

Basically the leaves have curled up, lost their healthy green and have turned yellowish. Pictures attached, can someone please help me out because I don't want to lose my little ladies. Here are the pictures of the plants



Please excuse the camera quality, I don't have a better camera at my disposal.
Cheers,
Dan.

#1 yes, too soon to feed. seedlings get nutes from leaves first couple weeks.
#2 use base soil for seedlings, no nutes added, will avoid burning and ph issues in the future
#3 looks over watered to me. stick your finger into the soil second knuckle. water when dry but not too much.
#4 under watering, that's a big pot, doubt you are under watering.

you might need to start over with better soil - plastic solo cup - easier to control watering.

What prosperian said. It looks like plant #2 is toast. May be able to salvage the other one.

looking great can see a few oz of that shit........

Thanks a lot dudes, yeah I think that's a good idea really. I think I'll ditch the big pots for the time being, replant seedlings in a potting soil, wait until they're big and strong and then transfer them into a good NPK soil. I'd say over watering was the problem, and nutrients too soon. Big lessons learned though, I did a lot of naive things and made a lot of noob mistakes, next grow I'll have no room for deviation from what I'm told to do. Thanks a lot everyone.

We all make mistakes. It's part of the learning process. I killed my first 4 seeds. And several grows later, I almost killed my seedlings with poor drainage in solo cups. Just when you think you have the hang of things, Mother Nature will throw you a curve and humble you real quick! Good luck Danner.