Yeah the bioballs are only in the canister filter. I have heard regularly both here and elsewhere that they are simply not needed anymore with other means of bacteria colonisation, and improved knowledge about how the whole thing works. I have heard that there are many successful aquariums with no bioballs, relying on the live rock to supply effective bacteria colonisation.
I have never cleaned them since the tank was established, simply because I wasn't aware I had to, and figured that this would degrade the capacity of the filter to provide the bacteria colonisation factory.
I do water changes usually only when the water evaporates, which is typically 3-4 weeks. Depending on the specific gravity of the aquarium, I might use salt water, otherwise fresh treated water. Honestly I haven't had to use fresh water, as I get a fair deal of salt build up on my glass, so I am guessing that is why my specific gravity seems to be just a little below what the "ideal" is.
I also have a multi-purpose
HOB unit which skims nicely, but also has compartments for installing bacteria colonisation mediums (bioballs, matrix, etc) so I feel even moreso that I could do away with the bioballs over a period of six months. In fact I have about 4-5 times as much required matrix as my capacity tank requires, which would probably explain why whenever something dies in the tank my ammonia, nitrite and nitrates are zero. That and the fact that I have around 45kg of live rock.
I had a dead fish in there for around 12 hours, albiet a small fish, with no difference in those levels above.