Thank you all for your responses. I apologize for just getting back to you, we had a medical emergency in the family and I had to leave town and take care of him.
Actually, the place we bought the hot tub from had told me to chemically clean the filters and if that didn't fix the problem, they would come out and that it was still under warranty. We emptied the tub, chemically cleaned the filters, and still had the problem. So I called and they came out. They took the filters out completely, and it solved the problem. I wish they would have told me to take the filters completely out and try that first. It would have saved me a $130 house call. That's why I'm a little peeved and am looking elsewhere for my supplies. At least now I know what to do in the future. (Turn to you guys. ha!)
We clean the filters faithfully and empty and refill the tub 4 times a year. When we empty, we use the degreaser/chemical cleaner. (I asked about the pressure washer (cuz I thought it was a good idea too), but they said never use a pressure washer as it will damage the filters.) In between the emptying/cleaning times, we put the filters in the dishwasher. The filters are the originals that came with the tub. We bought the tub exactly 2 years ago. I thought about going with the regular filters too, just because I figure, replace the regular filters every year, or replace the TriX filters every 2 years. Six of one, half dozen of another. I just wasn't sure which one's worked for the Envoy and none of the websites I visited stated the Envoy specifically.
Again, thank you soooo much for all your help! I'll be coming to you from now on, before calling for service!