Been installing pavers for many years but yesterday got a call for something I have not thought of doing. I was asked by someone if I would clean the patio. I have to do some resetting of their patio (I did not do the install) and they also asked me to clean the dirt and in some cases mildew off. I have a powerwasher. What would you guys suggest I use for a cleaner. I know I will have to be careful not to destroy the pavers with the powerwasher. Any thoughts? How would you price it?