Originally Posted by kfish
If the tank is filtered, 2-3 50% changes a week (vacuum the substrate during one of those changes, the other two water only) is enough.
I have a 3.5 filtered, CYCLED tank. It IS possible to cycle a small tank, but there's a far greater risk of mini-cycles and things going wrong in a tank that size, so frequent testing/water changes are a great idea. In my (very heavily planted) 3.5 g I do two 30% changes per week, and the tank has been utterly stable for months. If it was un
planted, I'd increase the % by a lot or not bother with the cycle and do 100%'s once a week.