I used to just use a 2300psi PW I got from Lowes, but it would take forever to clean a bay. Soaks your boots and pants too. I got the Mosmatic surface cleaner from KR and a new 4000psi 4gpm PW, and I don't have to spend hours cleaning anymore. Together they do a great job on the north side of the bays where green mold appear. For the entrance and exit I use a sweeper attachment to the PW and that cleans my asphalt pretty good.