There are several products on the market advertising that they will help keep your TPOroof spotless. The truth is, nothing quite works like a simple power wash. We recommendyou clean your TPO with a power washer at least once annually to prevent mold growthand keep your roof free of dirt and debris. Many manufacturers include anti-fungal oralgaecides within the TPO roofing, but they can lose effectiveness over time, and regularcleaning is needed