Internal Filters

These filters are great for beginners, they are relatively cheap to buy and small in size. They can work very well in smaller aquariums as long as they are maintained regularly. Each filter has a output flow rate and I would recommend that you choose a pump which will filter 3 to 4 times the volume of your water an hour. Internal filters do not have a great volume of filter material. This will mean that the foam can clog up quite quickly, so a weekly clean is necessary. The filter is best placed in the back corner of your tank. They are normally attached to the back of your aquarium with suction pads. Click here for information on specific products.

Sponge Filters

This works in a similar way to the under gravel filter. Air is forced down a plastic tube, which causes a flow of water through the sponge. This is best used as a supplement filter or a filter for a fry tank.

External Filters

These filters are for larger tanks generally 100l or over. They can also be used on smaller tanks where you want a larger flow rate or greater filter material. They are plastic containers, which you store below the aquarium. They have a pump which draws the water from the tank though a hose and flows it through the filter material then returns the water to the aquarium via another hose. External filters have loads of room for filter materials and you can use both mechanical and chemical materials. These filters can last for about 3 or 4 months before any maintenance is required. They are more expensive than other type of filters but are well worth the money. Click here for information on specific products.

Undergravel Filters

This is one of the cheapest ways to filter your tank. Under gravel filters is where water is drawn through the gravel, which sits on top of a plastic sheet placed on the bottom of your aquarium. The water is normally pumped using an air stone in a vertical tube attached to the plastic sheet. The air stone forces the water to go up the tube, which creates a current of water going from the bottom of the aquarium to the surface. I would not recommend this method of filtration as the gravel can become easily clogged and can create a major health risk to your fish.