Aquarium Canister Filter Anatomy Glossary Guide: Impeller Basket Pump
Aquarium canister filter anatomy in fifty words: a canister filter is a sealed external pressure vessel that pulls tank water through stacked media baskets and returns it via spray bar or lily pipe. Core parts are the impeller, motor head, sealing gasket, media baskets, prime button, hose barbs and intake strainer. Knowing the aquarium canister filter anatomy piece-by-piece helps you diagnose flow loss, leaks and noise, which is why this teardown from Gensou Aquascaping at 5 Everton Park covers each component with brand-specific notes.
The Motor Head and Impeller
At the top of every canister sits the motor head, housing a magnetically driven impeller that turns inside a wet-side rotor chamber. The motor itself is dry and induction-driven; only the impeller and shaft contact water. Eheim Classic 2215 uses a ceramic shaft and rubber bushings rated 8000 hours. Fluval 407 uses a self-priming impeller with anti-clog vanes. Worn impellers rattle audibly — replace every 3-4 years.
Sealing Gasket and Lid Clamp
The single largest failure point on any canister is the head gasket — a circular silicone or rubber O-ring that seals motor head to canister body. A pinched gasket leaks within hours; a dry gasket leaks within minutes. Lubricate annually with silicone grease (never petroleum). Eheim, JBL and Oase use spring-clip lid clamps; Fluval uses bayonet-twist lock.
Media Baskets and Stacking Order
Inside the canister sit 2-4 stackable plastic baskets that hold filter media. The standard stack from bottom to top is mechanical (sponge or floss) > biological (ceramic rings, sintered glass, K1) > chemical (carbon, Purigen). Water flows bottom-up in Eheim and most JBL units; Fluval reverses some models. Browse the aquarium filter range for replacement baskets and media.
Prime Button and Self-Priming Mechanisms
Restarting a canister after maintenance requires re-priming. Manual primers use a lever or spring-loaded button to pull a vacuum and draw water through the intake hose. Self-priming pumps (Fluval 07 series, Oase BioMaster) use a one-way valve and impeller geometry that lifts air automatically. Eheim Classic still uses a ball-valve manual primer that some users find finicky.
Hose Barbs and Quick-Disconnect Valves
Hoses connect via threaded barbs on the motor head, usually with a double quick-disconnect valve assembly. The disconnect lets you isolate the canister for cleaning without draining hoses. Hose IDs run 12-16 mm for small canisters (200-400 L/h) and 16-25 mm for large units (1000+ L/h). Mismatched hose-barb sizes cause flow restriction — use the manufacturer-rated hose only.
Intake Strainer and Spray Bar Output
The intake strainer is a slotted plastic cage that prevents fish, shrimp and large debris from entering the canister. Sponge prefilters slip over the strainer to catch finer detritus. The output side connects to a spray bar (broad gentle distribution), lily pipe (focused laminar flow) or simple nozzle. Match output style to tank type — planted scapes favour lily pipes for surface ripple control.
Brand-Specific Quirks
Eheim Classic 2215 (620 L/h) is the bulletproof workhorse — no media baskets, just a single chamber, virtually unkillable. Eheim 2217 handles tanks up to 600 L. Fluval 407 (1450 L/h) offers easier media access and a quieter motor. JBL CristalProfi e902 (900 L/h) sits in the middle with German build quality at a friendlier price.
Diagnosing Flow Loss
Flow drops 30-40 per cent from new in the first three months as biofilm coats media — this is normal. Sudden drops indicate impeller clog, gasket air leak or strainer blockage. Strip and rinse media in tank water (not tap), inspect the impeller chamber, and check hoses for kinks or biofilm build-up. Replace gaskets every 2-3 years.
Singapore Sourcing Notes
Eheim, Fluval and JBL canisters are stocked at the Gensou filter section alongside replacement parts. Local pricing runs SGD 180-280 for entry models, SGD 350-550 for premium units. Online marketplaces sell grey-market imports cheaper but warranties are limited to local-distributor stock only.
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