Remove as much debris as possible from the pool and spa cover before removing it. A quick sweep or hosing towards the skimmer can remove some of the debris. If the cover is a floating type without a roller, be sure to fold or place it on a clean surface. Otherwise when you place it back on the pool it will drag leaves, grass, dirt and other great algae food into the pool. If it is a mechanical cover system, a small amount of debris on top of the cover will slide off as you roll it up, meanwhile be careful to avoid the cover catching on abrasive or sharp surfaces as you drag the cover off of the pool.