Fish filtration is basically the removal of unwanted organic or non-organic materials from water, such as waste produced by fish. When you buy an aquarium you will need some sort of filtration, and as there are several methods it’s important to understand what is the most suitable for the fish you plan to keep. The filtration system you choose will also depend on your budget and the size of the tank you choose.
Without filtration the water in your aquarium will become polluted, which will poison your fish and they will then get very sick or even die. Most filters work by catching solid waste that can then be manually removed later and by biologically converting toxins in fish waste into less harmful nitrates that get removed during water changes.
There are several filters available but the most basic are probably internal power filters. These have a small pump on top of a box containing a sponge and are located within the aquarium. Although some tanks, such as Juwel aquariums, come with fitted internal filters.
An internal filter usually sits just below the water’s surface and water is sucked in at the bottom of the filter and drawn through the sponge to catch waste. The sponge contains friendly bacteria that flourish in the polluted water as it passes through, as this water is rich with oxygen. The friendly bacteria convert the toxins, such as ammonia, into the less harmful nitrates that can be removed.
It is essential to rinse the sponge every couple of weeks in old tank water, not in tap water, to remove the trapped waste, so that the filter can continue to work at the same rate. If you don’t clear the debris in it the filter might run slowly, which could affect the oxygen levels in the water.
Even if the instructions for the filter suggest rinsing the sponge under the tap, use tank water instead, as the chlorine in tap water will kill the friendly bacteria living in the sponge.
You can also get under-gravel filtration systems, but these are quite old-fashioned now although they are suitable in budget tanks. You can also get external power filters, usually in bigger, more expensive aquariums.
External filters, as the name suggests, are situated outside the tank, usually in the cabinet below. Water is sucked out of the tank and into the filter, where it is cleaned and then pumped back into to the tank.
External filters usually do not need cleaning quite as often as internal filters and they are a bit more versatile. An external filter is probably the best choice if you want to keep more difficult fish, as they are more sophisticated. This also makes them generally more expensive.
To decide what size filter you need look for one that states it is capable of running an aquarium the size of yours or even a bit larger. To decide which kind of fish filtration system you need research the kind of fish you want to keep and talk to some experts before buying one.