When I was really busy working to finish my degree, I skipped water changes for several months in my 5g RCS tank. I think I was able to get away with it because I had a high plant load in comparison to a low bioload (just shrimp). It was also a low light tank with no ferts or CO2. So the plants were able to use up the nitrates that resulted from the food and excrement from the shrimp. The tank also has a tight lid so I had little evaporation and didn't have to top it off.
Otherwise, I think a tank will always need water changes. However, it is possible to have a tank that requires fewer water changes. I'm able to do this with my low tech tanks. Again, the combination that makes it work is to have low light, no CO2, and no ferts with a high plant load in combined with a low fish load. I also have tight fitting lids which prevent evaporation, preventing the need for top offs (I do not do top offs). With these tanks, I can get away with 50% water changes every 2-4 weeks.
One thing I think that's important is to figure out why the water changes are such a pain because they really shouldn't be that hard. Usually, when someone complains about doing water changes, I find they're using buckets. Water changes are very easy when using a water changer.
alphabeatsco, how are you doing your water changes? Are you using buckets or a water changer?
