In my expreience I've found that under the right conditions any store bought soil will work and I am actually using Scotts top soil right now. Your problem is definitely the light and the containers you chose to start your seeds in. I use 16 Oz. plastic cups and any store bought soil. For water I use the 3 gallon containers with the spout that you can buy with spring water and reuse it by filling with regular tap water and let it sit with the cap off over night to let any chlorine and other minerals evaporate. For the first couple weeks I use 26 watt CFLs (100 Watt output). I've learned that you only need 1 - 2 of these bulbs for every 2 seedlings. Right now I have my very first plant from a year ago that I've taken 2 harvests from so far and is vegging for the 3rd TIME! It has 16 main colas, is about 2 feet tall and 3 - 4 foot in diameter, there is a 6 week old and two 3 week old plants as well as 3 clones ALL vegging under just SIX 26 watt CFLs. I admit the lights are well placed but in veg you only need about half the watts/lumens you need for flowering. I use 400W HPS for flowering BTW. For nutes I use Schults Veg and Schults Big Bloom along with Vitamin B1 and Molasses. That's all I've ever used and my results have been superb. Sorry for all the info I just wanted to show you and anyone else interested how easy it is with minimal resources. Best of luck.