Need advice: I have been hired to clean a long driveway with no living vegetation on either side, just some already dead grass. It has terrible tannin stains, and the appearance of striping that is already on the driveway tells me that customer (or another company) has attempted to clean it but with no success. I want to use my Xjet because I believe it will distribute my chemical stronger. But I will really fly thru chemical doing that. Recently I used just straight up 12.5% SH on smooth driveway and turned out beautiful, but this driveway is less than smooth with a rocky (yo, adrienne!) texture. Any suggestions?