Try Deltec if you want what is supposed to be the top dog for HOB skimmers. Dr Fosters and Marine Depot, Petsmart or even Petco is also ok for purchasing HOB regular filters. If your just in the market for a regular filter I would go for an Aquaclear and just run live rock in it for circulation. Or you could even make it into a pint sized refugium by looking up some DIY mods online.