black gold is a decent product...
i never had a issue with FF but i did have gnats and now that above mentiones it may have been my FF soil...
learn a bit of soil biology and you can make your own...will take about a day of research to figure out the basics.
FF is also extremey hydrophobic one it dries out...making it hard to give a thourogh watering..
a good mix of pasturized compost and pro mix is always great..so many different options out there...any way you go its going to take some effort to keep a good healthy ecosystem..