ive just cleaned my patio block paving with my new 13hp/15lpm/3600psi loncin pressure washer(no turbo nozzle) it came up really well and no probs with the amount of pressure, i was also using my northen tools fsc but i couldnt get the black pitted spots off unless i did it with the lance about 1cm away!! i also scrubbed in tfr and bleach with a brush 1st but had little effect, can any1 help? also can sum1 explain exactly wot a turbo nozzle does? (if theres different sizes etc) best regards mike.