Don't wear good jeans. Rinse before and after thoroughly and then some, I would also forewarn the homeowner that they will most likely lose the blossoms on their flowers. Even though the plants were okay, it still burned the blossoms and made them shrivel.
I use Pool SHOCK.. to Clean Concrete when bleaching is ness.. but for the most part hot water 3500 psi @ 4gpm at 200 degrees and a surface cleaner does pretty good by itself.
I can't afford a hot water machine at the moment.. Are they really "all that" ?
I do think there's a big market or driveway /conctrete cleaning here in Altanta.. I would like to in the future, get the most efficient equipment..available, and make some BIG money. !!!