MG soil works perfectly fine FDD uses it and he has badass grows. Just get MG moisture control. That carbon filter might be unneccesary look into TiO2 CFL's I hear they kill 100 percent of smell and also emit extra light for your grow. I have two coming in the mail so I will tell you about them when they get here.
I agree though your friend is a fg (what my O chem teach calls fucking geniouses). This is brilliant, cheap, and obviously produces. In 5 months I will be building one with those massive rubbermaids, hopefully no filter, low dB stealth computer 80mm fans and using 8 42 watt CFL's for flower.