I am new to WFP and got a complait, i tested my water which was correct. So i could'nt work out what was wrong(spots on the windows) When i thought it through i remembered cleaning a conservatory roof with soap ,very dirty moss ect.then washing it off with my WFP, do you think that some soap and dirt would stay in the brush of the WFP then be left on the next windows or was it that i had the flow rate to was to low,( did'nt realise low flow rate could leave marks) thanks for any replys