Well you can just order a bubble kit at amazon for like 40$ brings all 5 micron bags
http://www.amazon.com/Virtual-Sun-BM505G-5-Gallon-Extracts/dp/B00550EIDA/ref=sr_1_1?ie=UTF8&qid=1337274324&sr=8-1
I would not go with miracle grow its just a bad potting soil all around i would suggest you see if your local hydroponic store has some Fox Farms Ocean Forest+a bag of Perlite to add to the soil for it could drain better