Every aquarium needs good filtration. They come in varying shapes and sizes, Internal and External. The choice is up to you, but to give you a little help here are some pointers. Undergravel. This is just what it says, a tray that sits under the gravel on the base of the aquarium, it has the ability to draw water through it and works on a vacuum principal. In its most efficient form there should be at least 2” to 2 ½” of gravel on top. There is always at least one up lift tube fixed to the tray. It is then powered by an external air pump. This has air line and an air stone that fits down the up lift tube or alternatively a Powerhead that sits in the top of the tube. The uplift tube and Powerhead should always be submerged by approximately 1”. Powerheads can also be used on their own to create flow in an aquarium, this is especially beneficial in tanks such as freshwater river dwelling fish who’s natural habitat includes ebbing and flowing water. It can make your aquarium full of healthy fish that will live and spawn naturally. Powerheads are vital in the Marine aquarium as this environment needs constant water circulation for its inhabitants to thrive, corals and other organisms rely on the flowing water movement to enable them to feed. Fish need the flow to keep muscles strong and healthy. Powerheads can also be used on wave making machines to create an even more natural habitat as this creates the surges of water naturally occurring on a reef.