Canister filters are considered superior to sponge filters, hang-on-the-back filters and internal filters as they typically have a larger media capacity. The mechanical, chemical and biological media in a canister filter are often situated in separate media baskets hence less beneficial bacteria gets flushed during a filter clean especially compared to a sponge filters or internal filters. .
Most canister filter uses two to three different coarseness mechanical media. The idea behind this is so that bigger waste particles get trapped within the coarse media first and get broken down before progressing onto the finer media. This process allows for longer period before the filter media gets clogged and needed cleaning. Internal filters and sponge filters generally have a very fine sponge which gets clogged very quickly and will compromise flow rate and efficiency.
Factors to consider before buying a canister filter:
1. What fish are you planning to keep (amount of bioload)?
As a general rule, aim for 4 times turnover rate (aquarium volume x 4) on low bioload fish tanks and 6-10 times turnover rate for large bioload tanks such as for African Cichlid and Goldfish.
2. What is your budget?
The most value for money and entry level canister filter is the Aqua One Aquis and Nautilus range.
3. Which canister filter has a primer for easy startup?