Raw or improperly processed rice hulls used as a coco/soil amendment can leach compounds that significantly lower substrate pH, causing nutrient lockout and deficiencies.
Dakota explains that non-parboiled rice hulls in the Autopot coco mix caused major pH swing and nutrient deficiencies in the Peyote Zkittlez and Blood Moon Gelato. Some rice hulls also germinated into weeds. The fix for the next run is switching to perlite. 'The rice hulls were what were causing the issue on the last run.'
Discussed in: Ep 005