I started out wit an 18" hammer head and did very well with it. Last season the time came to get a new one, I got a 20" BE whirl-a-way and haven't had any luck with it. I've tried several different nozzles, adjusting the height of wheels, and my hammer head that's beat up and 1/2 the price cleans better. I plan on getting an 8gpm+ this season. My current machine is a 5.5 gal 3000 psi what surface cleaner would u recommend for me?