We thought our deck was lost to black mold spots. We had tried several cleaners available in hardware stores to no avail. Our contractor encouraged us to order the Corte-Clean because we had used it 3 years earlier and was happy with the results at that time. It worked great on getting off the black mold spots and unlike with all those other cleaners the spots have not returned. Our contractor was so impressed with this product that he kept the empty bag so he can recommend it to future customers. We'll never waste time and money on any other cleaner. Thank you Corte-Clean!