Powerfilters are the easiest and least complicated of all the filter systems available nowadays.
It simply pulls the water into the filter media and pumped back to the aquarium.
It improved over the years and there are a few kinds available.
External
It hangs on the outside of the aquarium and is powered by a motor.
It looks like a big square cup! It has filter floss or sponges and activated carbon filter media.
Water goes through the filter by a U-shaped intake tube.
It goes and flows to the media and then pumped back to the aquarium either through another tube or a spillway.
It provides mechanical and chemical filtration. The biological filtration is established when the filter matures and bacteria colonize it.
So, it provides all three kinds of filtration. It also circulates water, which provides aeration and water circulation in the aquarium.
These kinds of filters are easy to maintain. You can simply replace it. Most comes in simple cartridges.
They are ideal for aquariums that also have an undergravel filter system or a live rock.
Biowheels
Some of the external powerfilters come with a smart option called biowheel. Biowheel comes in contact with air and water in the filter. Water moves through the filter, the wheel spins and expose the bacteria that live on the wheel to air and the water.
This system provides enhanced biological filtration when bacteria get exposed to air making it efficient for the conversion of ammonia.
Biowheel also let you keep the bacteria even if you have to replace the internal filter media. IT is available as an external powerfilter or as a separate unit that hang on the back of your aquarium. It is powered by a powerhead or a canister filter.
Internal
These are similar to external powerfilters but are placed inside the aquarium.
The benefit of this kind of filter is that they provide an excellent water movement since they are usually placed near the bottom of the aquarium which is good if you have a “dead spot” in your aquarium that needs water flow.
But a disadvantage is that it takes up valuable space inside and blocks the view. But newer versions are now available as decoration inside your aquarium which you can use for aquascaping.