I have done both. Either way will work. If your water condition change it would be a lot safer making smaller changes. For me that would be more work then I would want to do. I change once every two weeks about 30%. When I was breeding fish I change over 10% every other day. But that gets to be a real pain as time goes on. What ever you do make sure it doesn't become a burdened.
Last edited by Clear Water; 07-13-2015 at 02:02 PM.