Replace the hose to the Macerator?

[missingdigit]

I'd like to replace the factory 3" hose between the coach drain and the inlet to the macerator pump. I have an (almost) constant sewage odor in the plumbing bay. I've read that the factory hose is permeable and is the cause of odors. Can anyone recommend a source? How long does it need to be - looks like 4 feet. Everything I have found requires buying a long length. Help very much appreciated.

[Dutch Star Don]

I just bought a Rhino sewer hose (good quality) and cut it up to fit. No more smell.