This is one those questions that gets anwers on both ends of the spectrum. You will get answers like " I use it in every tank and have no issues" and "I never use it and have no issues". It can be helpful at times, but people tend to over medicate, luckily there is no harm in using it all the time other than a lighter wallet. I will add some a couple times a year, well, closer to once a year, and "I have no issues".