From your background, you should already have a good idea as far as chems....it's acids, caustics, or bleach.....the job determines what is to be used. I know what "we" should be charging, the question is what should "you" be charging.....I have no answer to that....only you know. It could be as low as $.05 per sq. ft. or as high as $1.00 per sq. ft......depends on the situation & job....many factors play into pricing......Good luck!