Hello des,
Sometimes a picture is better, not sure what machine your referring to but a decent prsssure washer would shift that for you.
If u now thinking about a machine best to get in touch with Rutland pumps, a Honda gx390 with lances and hoses won't cost £2000 if u want to add a whirlaway they about £350 or so. There won't be a need for extra costs on each job, maybe a bit of maintenance but that's it.
If u wanting a chemical to put down just nip over to general cleaning and find posts with " hypo "or use search bar
Matt