Freshwater

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Part I: Aquarium Basics
Filters that have alternative media, so that you can replace one part without
losing it all, are better than the completely disposable type where you lose
the whole bacteria colony when you throw the only source of filter medium
away.
The filter box or instructions indicate which parts of the filter you need to
replace and when to replace them. For example, a power filter with bio-wheels
(see the section “Power filters,” later in this chapter for more on bio-wheels)
would be better than a power filter that only has compact floss and carbon
pads that have to be replaced when the pad becomes clogged or the charcoal
is no longer active. The reason for this is that the bio wheels will retain beneficial
bacteria even though you are replacing the pads.
Chemical filtration
Chemical filtration takes place through mediums such as activated zeolite and
activated charcoal, which absorb chemicals and dissolved minerals as water
passes over them. Proper chemical filtration helps keep your aquarium water
clean and sparkling.
You generally find activated charcoal in corner, undergravel, replaceable
uplift tube heads — and power filters. Replace the filter medium according to
the manufacturer’s instructions. You should replace the medium once a
month in most cases.
Sifting Through Filtration Systems
Once you understand the importance of filtration systems and what they do,
you need to know what types of filters are out there and how they work. The
many types of filters on the market fall into several categories as far as function
and purpose are concerned. Technology is advancing rapidly, and a few
new systems combine the best aspects of several different filters.
Undergravel filters
An undergravel filter is one of the best systems for almost any type of aquarium
setup and has been around for a long time. We recommend starting with
an undergravel filter and building up from there. You can combine a good
mechanical/chemical filter combo (such as a power filter) with an undergravel
unit and have a complete setup. You can use an undergravel filter with any
type of system, and it’s an excellent tool for creating good biological filtration.