Answer:
Thank you for your question. Routine water changes are always recommended regardless of the type of filter media you employ. As a general guideline, a monthly 25% water change is recommended. However, smaller, more frequent water changes (15-20% every 1-2 weeks) are preferable for heavily stocked aquariums or aquariums with large fish. Learn more about the importance routine aquarium water changes. http://www.fosterandsmithaquatics.com/pic/article.cfm?c=3578&articleid=2172&d=158&category=263