When opening in the spring, the turn-around time from Winterized to swim-ready pool can vary. A number of factors effect the time, including: surrounding greenery , condition of the pool at closing, the fit and type of cover, time of year (the later in the spring that a pool is opened the greater change of an algae bloom from rising water temperatures) and the quality and type of filtration system. As a general rule of thumb a DE filter can clear up a pool within 1-3 days, a sand filter 5-10 days, and a cartridge system can vary widely based on the size and condition of the filter elements, and how often they are disassembled and cleaned. Cartridge filters are not an appropriate filter media for the Mid-Atlantic area and areas north of here, as they need to be manually cleaned multiple times during the start-up process. Further south, where pools are in operation year round a cartridge filter can be a sound choice.Once the pool water is clear, debris removal will generally take 1-2 visits to have the pool looking clear, blue and free of debris. It is best to open your pool at least 10 days before you actually plan on using it, especially if you have a sand or cartridge filter.