So i have an empty 20g long tank and im not really looking for a reef but more just clownfish only. Id like to not go through a heavy cycle so im wondering if a bare tank would be okay to highlight the fish? I have a smaller marine light and a filter capable for 30 gallon tanks and a small power head and heater. Im more curious how id need to treat the water. Is rodi necessary for fish only? Is a cycle even necessary with no sand or rock???