Only got 29s right now so I just grab the 5g bucket and the grav-vac. Do some light vacuming in the open areas and fill the bucket. Dump in the bathtub, and start filling it up with water about the same temp, add prime. put the bucket up a little higher than the tank and syphon the water back into the tank. Repeat in two days, once a week move the rocks around and suck up that filth.