While the choice of filters can seem vast, all fall broadly into a few camps, making choosing the right one an easy task. Tom Ackrill explains.
TOM ACKRILL Tom runs the Freshwater Fishkeeping Facebook group and has a passion for helping beginners
BY NOW we all know why filters are important, but confusions always surrounds what kind of filtration is best for a setup. In days past, the undergravel filter (UGF) was king, whereas now we have a range of options including internal, external, hang-on-back (HOB), and sump systems. Each of these have their own pros and cons, and each have their own place in the hobby, but which is best for you, and how do you go about making the right purchase?
Internal canister filters
The likeliest first exposure for most people is internal filtration. With a lot of hobbyists, the first tank is something on the smaller side, quite often sold as a complete kit, with all the necessary accessories. Generally speaking, in smaller tanks these kits will include an internal filter of some form.
The first great advantage with an internal filter is simply that; they’re inside to the tank. There’s zero pipework coming in or out of the tank, so any mechanical failures won’t result in a loss of water. They also have advantages when it comes to space, something of a premium in modern living, as there is no need to have an aquarium with a dedicated cabinet to house the filter. A simple worktop set-up in a kitchen, for example, with the internal filter inside, minimises the footprint of the aquarium.
Different manufacturers approach internal filters in different ways, and Fluval in particular showcase a range of capabilities—Fluval’s U-series of internal filters have probably been used by every aquarist in the country at some point, and with the development of the Fluval Flex aquarium with its rear compartments effectively being a combination of sump and internal filter, this is a brand that is well-known.
But there are also some disadvantages. As internal filters are typically quite small (in order to minimise their obtrusiveness) the amount of space available for mechanical and biological media is also limited.
They also lack the potential for customisation that larger external filters have. In many cases, internal canisters are designed specifically to take various sorts of proprietary inserts—filter floss, carbon, or other media cartridges and pouches. This can leave an aquarist feeling ‘locked in’ to their particular brand, or scratchin
