I can't say much about your problem, but can give you an advice for cleaning and sterilizing (my style). I don't use any special products or cleaning products. What I do is boiling water and wash every peace I can with hot water as fast as possible to keep high temps. And to not to burn I use one cotton hand gloves and on them I put 2 pairs of rubber gloves. I wash everything in the bucket (dwc bucket) and in same time I'm washing bucket as wel, I always try to cover as much surface with hot water as possible...Sometimes I use 5-7 kettles.
BTW use same technique for my aquarium, my fishes like when aquarium/filter is clean without cleaning products