well if you want to kill off bad alge just put it in a trash can with a heater and good water flow, with no light at all, wait about a month and put it in your DT, hair, bubble, cyno will all die off
note: the surface of the water must be moveing well or the rock will rot in the trash can, and when you break the slime on the top of the water be ready to run....it will stick like a dead cat under your bed haha