BMK: Ahh-Some will make the mold clean up on the shell much easier. With the tub fairly full and the water heated to at least 90-95 degrees, add a few level teaspoons of the gel to the water. Be sure the filters are out of the filter well. Ok to place them inside the tub while Ahh-Some is working. Increase chlorine sanitizer level to at least 10-15 ppm. Run the jets intermittently. Wipe any sticky stuff that may accumulate at the waterline before it dries and hardens up. wipe the interior with the tub filled with a soft brush or towel. Skim off any clumps of white coagulated gunk that you may see. Shut the tub off overnight and let the product soak in. In the morning, add another level teaspoon or two of Ahh-Some. Run the jets and air intakes wide open for 15 minutes. Drain, rinse and wipe. Your mold should be gone. We do this all the time with tubs that are emptied and left for short times and mold develops. Always re- fill the hot tub with a hose going into the filter well for a perfect and fast prime. Rinse the cleaned filters and place back into filter cavity. You are all set. Be sure to splash water from the tub that has Ahh-Some in it on the underside and top of the spa cover. You will have mold there that needs to be dealt with.