Instructions
Over the Side Filter
Purchase an over-the-side filter and assemble according to manufacturer instructions, which typically requires inserting the intake tube and filters.
Hang the filter over the side of the aquarium so that the intake tube is submerged in the water and the cartridge box hangs over the outside.
Plug in the filter and watch to make sure the water begins flowing. This should take less than a minute.
Powerhead
Purchase a Powerhead filtration system and assemble according to manufacturer instructions.
Insert the filtration cartridge into the housing, and hang over the side of the tank, submerging the filter below the water surface.
Change the cartridge when it appears to be dirty. This may need to happen as often as every two weeks.
Air Stone
Purchase an air stone kit. This should come with an air pump and plastic tubing.
Connect the tubing to the air stone and the air pump.
Place the air stone inside the fish tank in the desired location, and submerge the tubing under the gravel to hide it.
Plug in the air pump and watch for bubbles to begin forming on the stone. This should take less than a minute.
How to Oxygenate an Aquarium
Fish need oxygen to survive, just like humans. Fish produce carbon dioxide, which is released into the air from the water. Oxygen, in turn, is pulled into the water from the air, which helps the fish survive. Oxygen cannot be drawn into the water unless the surface tension is broken, so proper agitation and filtering are essential to sustaining and maintaining the health of your fish. Any number of aeration devices can be used to maintain the oxygen level in your tank.