the equipment isn't going from tank to tank.... for example same hose used to syphon before the fallow period as now without any sterilization... would these be a possible area of concern. The hose was in water prior to the fallow period and then kept in the trash can and used for water changes throughout that time. Any thoughts... I guess it won't hurt to sterilize it... sorry just asking for a friend of mine. ThanksPossible sources of parasites for sure. We aren't sure exactly how some parasites seem to migrate from tank to tank without fish transfer. Some thoughts are on aersol transmission. But more than likely, it's equipment, wet hands, and cross contamination is the result. I always clean, sterilize equipment from tanks with parasites. Bleach, rinse, rinse, rinse, dry. And if a particularly nasty parasite like Uronema, velvet, gram negative bacterial infections, etc. I do another step wit H2O2, rinse, rinse, rinse, dry.