Add-on devices for powerheads and water pumps can be great tools for creating wave-like water motion in small nano aquariums, or at the very least adding a little rotating direction to the flow. These small, often plastic flow diverters snap on to existing plumbing pieces in the standard all-in-one aquariums and water pressure usually moves plastic gears to drive the machine. These tiny wavemakers do a great job at first, and if maintained properly, but over time they tend to get calcium deposits on the gears, which prevents the wavemaker from spinning thereby removing almost all functionality. If you implement these rotating devices on your aquarium, be sure to break them down and clean them in your normal maintenance routine. A quick trip to the vinegar bath will do wonders.