TANKS & FILTRATION

Canister Filter

Pressurised external filter with stacked media trays, sized by turnover rate.

Setup stage Tanks

Unplug before servicingHands out of the water firstDrip loop on every cableTest before you dose30 ppm CO₂ ceilingCycle before stocking

Tanks

Technical line drawing of Canister Filter

Specification
Flow range	300–2000 L/h rated
Trays	2–5 stacked baskets
Effective turnover	3–6× tank volume per hour
Head height limit	1.2–1.8 m
Power draw	6–30 W
Noise	30–45 dB(A) at 1 m

Technical parameters
Planted tank target	4–6× volume/hour
Fish-only target	6–10× volume/hour
Head loss at 1 m lift	20–30% of rated flow
Media volume, 60 cm class	2.5–4 L
Service interval	4–8 weeks
Biological media life	Indefinite if not dried out

A canister filter sits under the tank in a cabinet, draws water through an intake pipe, pushes it through several trays of media, and returns it — usually through a spray bar or lily pipe. Because it is sealed and pressurised, water travels the full height of the media stack without channeling around it.

The number that matters is not the litres-per-hour figure printed on the box, which is measured with no media and no head height. It is the effective turnover: how many times the actual water volume passes through the filter each hour, after media and lift losses. A filter rated 1000 L/h on a 60 cm tank with a 40 cm lift typically delivers 550–650 L/h in practice.

Media is stacked in order of mechanical to biological to chemical: coarse sponge first, then finer sponge or filter floss, then sintered glass or ceramic biological media, then optionally carbon or resin. Reversing that order clogs the biological media with debris and turns the whole stack into a mechanical trap.

Safety and welfare

Unplug the filter before opening it, before every water change, and before reaching into the tank. The intake can trap a hand.
Fit a prefilter or intake guard. Small fish and shrimp are drawn into unprotected intakes and killed.
Never wash biological media under tap water. Chlorine kills the nitrifying bacteria you spent six weeks growing.

Using it well

Rinse sponges in a bucket of tank water during a water change — the same water, not new water, so the bacteria survive.

Clean one media tray per service rather than all of them. Cleaning everything at once resets the cycle.

A sudden drop in flow usually means a clogged impeller or a kinked hose, not a failed motor. Check those first.

Pairs with

Rimless aquariumSponge filter (as prefilter)Overflow boxSump systemCO₂ diffuser

Note. Parameters are conventional ranges across the category, not the claim of any one manufacturer. Nothing on this page is for sale and no outcome for any plant or animal is guaranteed. Simulator output elsewhere on this site is a simplified model, not a measurement — confirm everything with a test kit and the equipment's own instructions.

Canister Filter

Using it well

Pairs with

Works alongside