A replacement spa filter is available from Shepnell. They carry products from all the leading manufacturers including Advantage Electric, Aqua Tech, Blue Ridge, Dynasty, Hydro, Icon, Mater, Mountain Mist and Sunrise. The spa filter cartridges are grouped into series based on the approximate outer diameter (O.D.) of the cartridge. The diameter sizes range from 2 to 10 1/16. Approximate height is determined by measuring inches from endcap to endcap. A 5% discount applies for the purchase of three or more spa filters. Other hot tub accessories include parts, chemicals, cleaners, pumps, covers and more.