Frag tank on the cheap

[Spyd]

That would be ideal. Then the water is just coming from your system allowing no additional water changes for another tank setup. If you do branch off your display line, install 2 valves on the branch line. 1 to control the flow and 1 to shut-off the tank completely. This way when you do shut off the flow, you don't have to keep adjusting the one valve to get the flow just right. Just set it once and leave it then use the other valve to stop the flow completely.