I guess I normally average every 5-6 months on the bath thing. Usually have a chem-clean every 12-16 months. Costs a bit, but it totally purges the system. I think this is the first bath on this horn since a chem-clean early in the year, though, so the garden definitely had time to grow... And my main horn to boot! I was surprised there wasn't more crud in it than there was, especially considering how much coffee and wine I usually have during a gig (yes both - uppers and downers together baby!).