This is the replacement filter for all Discover series AquaRest Spas model years 2015 and newer (and DayDream 3000L). We sell both Pleatco (OEM) & Darlly (After Market) 28 sq ft. filters. Both can be used as replacement filters. According to the manufacturer, the filter needs to be cleaned at least once a month. When you clean your new filter, it's great to have a second one on hand as the filter you clean needs to dry completely before putting it back into the spa.  With a spare filter on hand, you can enjoy the spa without waiting for the other to dry! *AquaRest DayDream 35000 series and Dynamic Series spas use the PDM30 oval filter.