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How to choose a filter
The aquascape studio has no “filter model” parameter, but it does have tank size (nano through XL) and four biotopes. Before you buy, know what a filter is, why you need one, what media goes inside, then match tank size to scenario.
A filter is a loop that pulls water out of the tank, through media, and back again.
In home aquariums, the common forms look like this:
- Sponge / air-driven sponge: air pump pulls water through foam—gentle flow, lots of biofilm; nano, shrimp, quarantine, and fry tanks.
- Hang-on (HOB): clips on the rim, lifts water into a media box and returns it; easy to install and service—common on small and mid tanks.
- Canister: sealed bucket in the cabinet, plumbed with hoses; more media, usually quieter—the mainstay for medium and large planted tanks.
- Top / drip tray: a tray on the hood; water is lifted, drips through media, and falls back. Easy media access and strong aeration—popular for goldfish and cichlids. The waterfall agitates the surface, so CO₂-injected planted tanks rarely lead with it.
- Sump (overflow + under-cabinet): display overflows into multi-chamber media below, then a return pump. Highest capacity and room to expand—common on large or heavily stocked tanks. Cost and install are high.
- Back / side filter (built-in chamber): media lives in a rear or side compartment of an all-in-one tank—clean look; upgrade path depends on the chamber design.
- Undergravel (UGF): plates under the bed pull water so the substrate acts as media. An older approach; with planted thick beds it clogs and is hard to clean—rarely the main filter on modern planted tanks.
The form mainly decides how water is pushed, how large the media chamber is, and how strong filtration can be—as well as how well the hardware hides and how the tank looks.
Why buy a filter?
In a closed aquarium, fish respiration, waste, and rotting leftover food keep releasing ammonia (NH₃ / NH₄⁺) into the water. Ammonia is highly toxic to fish and shrimp; it is followed by nitrite (NO₂⁻), which is also dangerous. Without a stable colony of nitrifying bacteria, ammonia and nitrite climb fast—poor condition at best, acute death at worst.
Nitrification is roughly two steps: ammonia-oxidizing bacteria (AOB) turn ammonia into nitrite, then nitrite-oxidizing bacteria (NOB) turn that into nitrate (NO₃⁻). Nitrate is far less toxic; you dilute it with water changes, and planted tanks can take up some of it. Nitrifiers are aerobic—they prefer damp, porous surfaces with steady flow. Filter media is that “bed.” Without a filter, bacteria only cling to substrate, glass, and hardscape cracks: little area, unsteady flow, not enough for a normal bioload.
Buying a filter mainly does these two jobs at once:
- Mechanical filtration: water hits floss or sponge first and sheds feces, leaves, and debris. The water looks clearer, and later media stays less clogged. This layer gets dirty fastest—rinse or replace it regularly.
- Biological filtration: water keeps flowing through the pores of ceramic, bio-balls, sponge, and similar media; nitrifiers form a biofilm there and convert ammonia and nitrite into nitrate. That is the filter’s core value.
Circulation also mixes dead spots so oxygen, nutrients, and CO₂ (if used) spread more evenly, and mild surface ripple can reduce film.
What filter media is there?
Whatever the shell (HOB or canister), media falls into a few kinds. Order is usually: trap dirt on the intake side first, then house bacteria.
| Media | Job | Watch |
|---|---|---|
| Coarse / fine floss, sponge | Mechanical: traps particles and debris | Rinse or replace regularly so it does not clog |
| Ceramic rings, bio balls, lava rock, etc. | Biological: porous surfaces for nitrifiers | Usually no washing—only clean with old tank water when clogged and flow drops clearly; never blast with tap water. You can also replace media, but never all of it at once. |
Tank size and scenario lookup
Match the studio sizes: nano ~20–30 cm, small 30–60, medium 60–90, large 90–120, XL 120+.
| Tank size | Sparse fish / planted | Shrimp, QT, fry | Heavy bioload |
|---|---|---|---|
| Nano / small | Sponge or HOB | Sponge first; HOB needs an intake guard | HOB or a small canister; add a sponge as a second filter if needed |
| Medium (~60–90 cm) | Canister is common; HOB if budget is tight; all-in-ones may use back / side filters | Canister or HOB with a guard, flow mild; sponge as backup is fine | Canister; top / drip trays are also common; HOB baskets often run short |
| Large / XL | Canister is nearly the default; a sump is also an option | Canister with a guard | Canister (size up or dual) or sump; top filters suit goldfish and cichlids |
- With small fish or shrimp, always guard the filter intake and lower the flow, or livestock gets sucked in easily.
- Which filter form you use depends mainly on whether the look is acceptable, and how heavy the tank’s bioload is.
- Aim for about 4–5× tank volume per hour; with more fish, push toward 5–6×.
Things to watch
- Buying the biggest “rated liters”: Ad volumes are often empty-tank numbers and run high versus real installs. Media volume and adjustable flow matter more.
- Shrimp tanks with no intake guard: Fry into the intake is routine. A sponge filter, or a sponge sleeve on the intake, is the baseline.
- Scrubbing media clean, or replacing it all at once: Nitrifiers live on the media. Rinse dirty mechanical pads; keep the biofilm on biological media, and never swap every layer in one go.
In the aquascape studio, set tank size, biotope, hardscape, and substrate first, then pick filtration from the table. For choosing the tank itself, see how to choose a tank. Details worth adding? Tell us via Contact.
2026-09-30