i own a small maintenace business and was told that i could use chlorine in a liquid form (bought from a pool cleaning company) as a cleaning agent on roof tops. the roofs are shingle or slate roofs. should the chlorine be apply to the roof in concentrate or should i diloute with water. also what is the best chemical to use for cleaning mold, mildew, rust or oil stains. if anyone could assist me that would be great!!!