In reality I feel it is possible to run a tank without using chemicals or having to do weekly water changes. It is purely a question of finding the correct balance between fish and plants......too many fish and associated feeding no matter how good the filtration is ammonia will go up and up. So plants are key and maybe also use an under gravel filtration system also. We have had the tank 4 weeks now and had fish thrown on us and not changed any water out yet.I have never used dechlorinator, I believe that even with chloromine in the water it would be possible to do water changes without dechlorinator. With Chlorine I know that with an acid tank and planted to about 50% it is possible to do 25% water changes weekly with out any problems. There will be a level that the same is possible with chloromine in the water. What that combination is I have no idea and have no way of figuring it out. But I would love someone to figure out the combination that works. As aquarists we tend to throw way to much stuff into our tanks. Fish don't need or want to live in a chemical soup.