Aquarium Undergravel Filter

This is a small under-gravel filter I modeled up for a small fish tank my mom has. The tank itself is manufactured by Marina and called the Cubus. It is a 6 inch cube which only holds 0.9 gallons of water. She was intent on using it and didn't want something in the tank that would take up space. So I came up with this so that there could be at least some filtration for whatever she decided to put in there.

The base is 110 x 110mm and the uplift tube is 100mm tall. For those that don't know how an under-gravel filter works, you drop an air-stone that is attached to an air pump down the uplift tube. As the bubbles rise to the surface, they also pull water up with them which is replaced by water that is pulled down through the gravel creating circulation.