Looks like:
...your soil could use some perlite. (or a 'lighter' soil) Yours kinda looks like a clay-based backyard garden soil.
...'window' lighting is inadequate and likely their schedule is interrupted often with room lights and street lights. Not at all optimal. CFL's on a timer (or left on 24 hrs a day) will help dramatically, and a 400w MH would work even better, but you'd have to come up with a better growroom set-up for both. Keeping light out during dark periods is as important as giving ample light during lights-on. This is especially true during flower, but you're just vegging till a spring transplant, right?
...you are inviting bugs by using the seltzer water, and it tends to clog (gum's-up) the pores on the leaf, making respiration impossible. It does make your leaves work like flypaper to capture gnats, tho. (makes surrounding walls sticky, too)
...with the MG (All Purpose - 12-4-8) I was using 1/2 tsp:gallon, twice a week. (been using Fox Farms with great results for the past few years, tho)
...do you have a fan on 'em to strengthen the stems and provide fresh air?
...'filtered' water? You'll likely want a calcium suppliment, like CalMag Plus, or something similar.