Posted by @Chris_Lewis · 14h ago
All three can keep fish healthy — the right one depends on your tank and stock.
Sponge filter. Cheap, dead simple, and gentle. Runs off an air pump, provides excellent biological filtration, and won't suck up fry or shrimp — which makes it the default for breeding tanks, shrimp tanks, and quarantine. Downsides: little mechanical "polishing" and the bubbling air pump. Great as a first filter or a backup colony you can move to a new tank to instantly cycle it.
Hang-on-back (HOB). The easy all-rounder for most community tanks up to ~55 gallons. Good mechanical + biological filtration, simple to maintain, widely available. Pick one rated above your tank volume and you're set for a typical community.
Canister filter. The most capacity and flexibility, and the quietest. Best for larger tanks, heavily stocked tanks, and planted tanks where you want strong, customizable flow and lots of media. Costs more and takes longer to set up and clean, but it's the workhorse for serious setups.
Rule of thumb: match (and slightly exceed) the filter's rating to your tank volume, value biological capacity over flashy mechanical claims, and never clean all your media at once in tap water — you'll wipe out your bacteria.
Your turn: tell us your tank size and what you're keeping (community? shrimp? big messy fish?) and we'll recommend a filter type and rough size.