Here's a neat thread I found where a guy didn't do waterchanges for 4 years or so. Tom Barr even said the plants would break down the minerals on page 2, which i beleive is the page I'm linking http://www.plantedtank.net/forums/t...m/50456-zero-water-change-20-75-update-2.html
So it may very well be that a fear of mineral and organic buildup is not a factor.
