Can anyone tell me if a power washer would take green mold off indian sandstone slabs on my patio. Only had this work done in the summer and indian sandstone was highly recommended. Can't believe there is green moss/mold coming up already. Would a power washer be the answer and if so could anyone recommend one. Have seen them priced from about 100 euro up to 800 euro. B&Q have them but I wonder would it be a worth while going North to buy one. Any info would be appreciated.