of the cartridge dispenser to replace a spent cartridge the user merely removes the spent dispenser cartridge out of the holder and secures a fresh cartridge into position fig4 shows a top view of the cartridge holder 11 illustrating that the holder 11 has an elongated shape a top region 11 b can carry product identifying information or instructions on the use of the holder with cartridge dispensers preferably holder 11 is made of a lightweight material and includes rounded corners so as not be injurious to the occupants if allowed to float in a spa or hot tub containing the holder and the occupants fig5 is a bottom view of cartridge holder 11 showing the side by side location of recess 20 for holding a first cartridge dispenser and recess 20 a for holding a second cartridge dispenser as the recess 20 and 20 a and the cartridge engaging members therein are identical only one is described herein cartridge holder 11 is hollow and includes a set of four holes 11 c allow for fluid to flow in or out of cartridge holder 11 located in cylindrical recess 20 is an annular stop 21 for engaging the top of a dispenser cartridge which can be centrally located in recess.