Filtration is the life support system of your aquarium. Choosing the right filter for your tank size and fish community is the single most important equipment decision you will make in fishkeeping.

Hang-On-Back Filters

HOB filters are the most popular choice for beginners. They hang on the tank rim and provide mechanical, chemical, and biological filtration. They are easy to maintain, affordable, and effective for tanks up to 75 gallons. Media cartridge replacement is straightforward.

Canister Filters

External canister filters provide superior filtration for medium to large tanks. They hold more filter media, allow customizable media arrangements, and operate more quietly than HOB filters. They require more complex maintenance but need cleaning less frequently.

Sponge Filters

Powered by air pumps, sponge filters provide gentle biological filtration ideal for betta tanks, shrimp tanks, fry rearing, and hospital tanks. They are inexpensive, reliable, and create minimal current. They lack chemical filtration capability.

Flow Rate Considerations

General guidelines suggest the filter should turn over the tank volume four to six times per hour. A 20-gallon tank needs a filter rated for 80 to 120 gallons per hour. However, some fish species like bettas and shrimp prefer lower flow rates.

Filter Media Types

Mechanical media like sponge and floss catch particles. Biological media like ceramic rings and bio-balls house beneficial bacteria. Chemical media like activated carbon removes dissolved chemicals and odors. A complete filtration system uses all three types.

Maintenance Schedule

Rinse mechanical media in old tank water weekly. Replace carbon monthly. Never replace all media at once, as this destroys beneficial bacteria colonies. Alternate media replacement to maintain biological filtration continuity.