Hot Spring Spas Tri-X Ceramic Cartridge Filter 4 pack, original Hot Spring replacement filter. The Tri- X Filter is a Factory Original Hot Spring Replacement Filter. This ceramic fiber cartridge filter was introduced in the 2005 Hot Spring high performance spa models. In 2006 the Tri–X became available as a replacement for the common polyester filters. The unique design enables it to filter twice the water per minute than a common filter. You don’t have to clean it as often either! 6″ diameter x 10.5″ Long. 73250 Tri-X Ceramic Cartridge Filter is for the following models.