Heavy 16 A&B bases are pure chemical fertilizer there are no organics in it. The only products that are remotely natural that they offer is the Fire & Prime as it has kelp and some other stuff in it like molasses.
As for it being sterile you should use h2o2 (Hydrogen Peroxide) to sterilize your buckets & equipment between nutrient changes and always add supplemental h2o2 to your reservoir directly per instructions. PREVENT PROBLEMS BEFORE THEY OCCUR (AN OUNCE OF PREVENTION IS WORTH A POUND OF CURE)
A product that will ensure your water & nutrient solution stays clean is UC Roots by Cultured Solutions. It's 1% Hypochlorous acid, used at a rate of 5-10ml per gallon in an active system and 25-30 ml in an inactive system (between grows).
Personally my water has a tendency to cause brown roots even when ran through the Hydro-Logic RO-150 system with updated filters.. It's well water so probably a bacteria or virus getting past the RO membrane. I've bleached everything past the RO membrane so other than that it'd have to be airborne.
Good luck with Heavy 16 I ended up discontinuing it when the quality was kinda shit. The appearance is almost like PGR weed on the strains I grew and the buds were like ROCKS. Decent weight but definitely bumped my Medical grade down to a recreational grade in my book. Flavor wasn't there and neither was potency.
