I am looking for some general information regarding the different nozzle sizes and their uses related to flat work. My machine came with the standard set of 4 quick connect nozzles and I am interested to hear what they should be used for. For instance, I have heard several times that people use the 15 degree for gum. Is that the same nozzle I want to use for general concrete cleaning? I also know that I should be very careful with the 0 degree. Any information would be helpful.