Soil is my own brew with perlite and some bat guano for good measure. I've been using this medium for many years...not just for weed plants either. It does quite well for the first 4 weeks or so; especially for seedlings. I know what I did wrong with the watering so this time will be much better. I'm going to start them off with a 125w CFL and the 240w LED. When they get big enough to flower then I'll add in the 600W BS LED.
With this light available you should grow a monster.
I do not realize how you are going to use it.