Have a church covered in limestone . 3 yr old building . Dirt and black mold/mildew buildup . The building manager is worried about high pressure because he read somewhere on some website that high pressure is bad . I was planning on x-jetting with my m5 SH+lemonade +roof snot . Dwell about 15 minutes . Rinse with hot water high flow gpm. Bought some nozzles that will reduce pressure from 3500 to 1750. This is a huge church campus. Told him I would do a demo on a couple of pillars with limestone tops on them . Was thinking about hand pump spraying 12.5 % Sh with surfactant and low pressure rinse for show and to reduce customer anxiety . Should I dilute the hand pump pray or go hot and heavy to make it look real good and easy . When I do the whole building I was going to use about 3 gallons of 12.5% to 2 gallons of water. The manager knows I will bump up the pressure when I do the whole building to save time and get the job done but wants me to take it "Easy" for the demo because other people will be watching the demo . Any comments or concerns on this plan ?