Any product that suggests it is an alternative to water changes needs to be looked upon with suspicion. How does it deal with the build up of nitrates?? If it "locks" them up, then it would follow that they won't be avaliable for any plants that are present. If you're not doing water changes then it is most likely you won't be doing any gravel cleaning either, allowing dirt and mulm to build up which is detrimental to the overall health and balance of the aquarium. So I would say try it if you want, but it won't be as good as good old fashioned water changes which are an integral part of maintaining any healthy aquarium.