Methods, improved compositions and kits are employed that provide dosing and cleaning solutions containing a halogen-based oxidant effectively delivered to remediate microfloral and biofilm development on the laundering surfaces of enclosed horizontal axis washers. The improved compositions, and the methods and kits employing them, provide for effective remediation while minimizing and/or preventing detrimental effects upon halogen-susceptible surfaces of the laundering devices, including reduced corrosion and biofilm on interior metal and laundering surfaces.