Abstract: An apparatus and method for cleaning and maintaining Biologically Accelerated Treatment ("BAT") support media disposed within a fixed wastewater treatment tank is disclosed. The cleaning apparatus includes a hollow shaft and a perpendicularly placed diffuser having a plurality of orifices, which may also include nozzles. An air blower or a water pump is attached to the hollow shaft. The cleaning apparatus is inserted into a wastewater treatment tank, and either air or water is forced through the orifices or nozzles of the diffuser, respectively. The air or water generates a force that is directed toward the BAT support media to effect cleaning. In one embodiment, a hinge is provided between the shaft and diffuser to enable the diffuser to pivot downward, to a position close to parallel with the hollow shaft, so that the cleaning apparatus can be inserted through multiple risers that provide access to an underground wastewater treatment tank.