Filter Cartridge Replacement

[historyguy101]

Hi Everyone--

My wife and I recently bought a house that came with a hot tub.  We know nothing about hot tubs and the previous owners left us no information about the tub.  The keypad says Sunbelt Spas, Lucite.  I'm having a difficult time trying to find a filter replacement cartridge.  (The previous owners had the wrong type of cartridge.) The skim filter bottom is made by Waterway (serial number 515-6610) and I can't seem to locate either on-line or at pool/hot tub/spa stores what type of replacement cartridge is compatible with the Waterway housing.  Any ideas?!?

Thanks for your help!

[Dr. Spa™ Ret.]

Most likely, with the brand Unicel it's one of these;

C-4950    50 sq. ft. 4-15/16" diameter x 13-5/16" long

C-4970    75 sq. ft. 4-15/16" diameter x 23-5/8" long