I use what I get at the aquarium store. Lol. Works for me. 

Man there is so much when it come to organic growing, it makes my head hurt just thinking about trying to answer that question for you.

My best advice would be to get a book called teaming with microbes by Jeff lowenfields or TLO Organics by the Rev.

Im 3/4 way thru TLO Organics!!  My head hurts!!  LOL. but I'm hooked.  On a quest to figure it out!  Great book

Thanks Bob!