I am totally aware of it. I am re-using my old fish water for garden and lawn. All my plants are very healthy and fruits are getting huge huge without using any chemical. Just need to find a way to re-use it. I like the idea of algae scrubber and haven't seen anybody actually implementing the idea in goldfish world. Please let us know your result. You might want to keep result of how much your fish grow before and after using it.. Thanks.