Freshwater

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Part I: Aquarium Basics
pump sealed in hard plastic which you can insert into the top of the uplift
tubes of an undergravel filter system. You can also hang them on the tank (or
buy a fully submersible model) to provide good circulation in your aquarium.
Some models come with internal filter pads as well.
The really neat thing about powerheads is that they have adjustable valves to
regulate the speed of the airflow (thus increasing or decreasing the speed and
force of the water flow). This little valve is convenient (not to mention fun to
play with) in smaller tanks when you want to cut down the flow to keep the
tank’s inhabitants from being blown all over the aquarium or permanently
embedded in the glass walls. Powerheads also have a rotating outflow that you
can turn to direct the water flow to a specific area in your aquarium. (Or turn
the outflow straight up and have your whole family shower at the same time.)
Canister filters
A canister filter provides biological, chemical, and mechanical filtration. This
type of unit is very popular with hobbyists and is often used in larger aquarium
systems because they do such a wonderful job of keeping water in good
condition. A canister filter contains several media compartments (baskets)
that usually contain sponges/foam blocks, carbon (charcoal), and some type
of ceramic medium. The aquarium water is drawn through the filter via hoses
attached to a high-pressure pump.
Canister filters are capable of turning over several hundred gallons of aquarium
water per hour and have an internal motor to accomplish this task. Most
canister filters sit on the floor beneath the aquarium, but some models attach
to the back of the aquarium glass (“hang on tank,” also know as H.O.T.). You
can adjust the filter’s output to any part of the tank that meets your personal
desires. A canister filter can be very large, bulky, and unsightly, so make sure
you have a place to hide it in the aquarium cabinet or behind the stand so
that your house doesn’t look like a water-processing plant.
Fluidized bed filters
A fluidized bed filter is one of the best biological filters on the market. The
only drawback is that they can be very expensive and require a pre-filter to
remove particles. But if you happen to make a few extra bucks selling some
fry, it’s well worth the investment to purchase one of these units.
Fluidized bed filters are extremely compact and use sand as a filter medium.
The sand is continuously kept wet by water flowing through it and has a huge
surface area where a large colony of nitrogen cycle beneficial bacteria can
grow and multiply, as mentioned earlier in this chapter. This type of filter
improves oxygenation because the sand is constantly tumbled in a stream of