I have found that the flat surface cleaner i have,a whirlaway,is good at cleaning block but it has dissapointed me when attemting to remove all the moss from joints,i had my washer at full throttle and still had to go over whole job with turbo nozzle with was brilliant,if i was on a budget my first impressions are get the turbo nozzle before a fsc,i think as a novice i have believed the hype,unless my machine is faulty.