MG,WAL-MART,JUNGLE GROWTH.and other national brands are produced regionally.what this means is the MG you buy on the west coast is mixed from different stuff and at a different place than the MG on the east coast or southeast.this results in the grower ALWAYS having to modify the mix to their own needs be it foxfarm ,promix, or mg. Do you want to water your seedlings once a week? add just a little perlite.once a day?add a lot of perlite.PH to high? add peat moss or lime.Ya'll know what i mean?as for BUGS just assume your bagged soil has them and kill them before taking the dirt into your grow area.I dump my soil [after drying and adding perlite,lime,bone meal,etc..]into large black garbage bags and drenching with NEEM oil tie it shut and leave for 2 weeks. seem to work for me.