I've read you're supposed to bake it to kill any bugs. This last time I mixed 2/3 new FFOF, 1/6 old FFOF that I had just used until males showed up in it last time, and 1/6 of some sort of Canadian organic stuff.
I figured that since new FFOF is so "hot," that using the old stuff and the Canadian organic stuff would cool it off a bit.
I got bugs--fungus gnats. I killed them with a single treatment of $28-a-little-jar Gnatrol.
I think I'll use new FFOF next time; maybe mix it with what I have left of the Canadian organic stuff. I only need enough for eight three gallon pots--that's all that'll fit in my cabinet.