The old days of using caustic liquids like h2o2 to sterilise hydroponic systems are coming to an end. The modern approach is all about using Friendly bacteria. Bacillis Subtiliss GB03 creates a natural enzyme factory inside the reservoir or plant pot. Bacillis lives in harnmony with your roots protecting them from harmful bacteria like pythium. An advantage of this modern approach is that Plantacillin will only kill bad bacteria where as h202 will kill ALL bacteria both Good and Bad.