GotATub

I just became the proud owner of a used Savannah Spa Mirage which I think was the Home Depot brand back when they sold hot tubs. Now that they no longer sell hot tubs (at least here in Colorado) I'm looking for places to by stuff. The problem is as best I can tell, all of the part numbers in the manual are Home Depot part numbers. So to cut to the chase, how do I find out what kind of filter I need for a Savannah Spa Mirage, with a part number M-4326-HD? Should I just pull it and take it to my local spa dealer? There's a huge amount to get my arms around here (spa just installed last week), so sorry if this is a stupid question.