OK, lets see here.

The first thing I notice is that you are using a 400watt MH to grow from seed. seedlings prefer less light. a lot of growers start seeds/clones with fluorescent lights because of this. they are also cool to the touch so you can get em nice and close to the sprouts. HOWEVER, this shouldn't stunt the growth completely.

what exactly is "universal turf soil"? I've never heard of it. It looks like a very compact soil, which is no good for cannabis. the key to a good soil mix- for cannabis at least - is aeration. personally, I try and make my soil medium about 25% perlite at the least. 50% is optimal IMO.

Lastly, pH can make or break your plants. usually ph only becomes an issue in the later stages of vegetation as salts build up from nutrients. but its possible that your water supply or the soil itself is too alkaline or acidic. I'm currently in the process of adjusting my soil ph levels myself. it happens more often than you'd think. It may be worth your while to invest in a pH probe, or at least some litmus paper. just to get a general idea of whats going on pH-wise.

I notice you didnt answer the question about what nutrients you are using... are you using any? crappy solutions like miracle gro are great for flowers and stuff, but cannabis requires an entirely different diet. and... you shouldn't use any nutrients AT ALL until your plant looks like it needs it. its much easier and more effective to feed a hungry plant than starve an overfed plant.

It's also possible that you got a bad seed with bad genetics that just decided to stop growing. It's rare, but unfortunately it does happen.