Skip to content
AquaReefBasin

Gear

Filters

A filter is doing three separate jobs in one box: straining particles out mechanically, housing the bacterial colony that processes waste biologically, and — if you put media in for it — removing dissolved substances chemically. The second of those is the one that keeps fish alive, and it is the one nobody sees. That is why the guidance everywhere on this site is to leave the media alone and rinse it in tank water: you are not cleaning a machine, you are servicing a habitat.

Core job: turning water over and housing the bacteria · 2 products listed

Read this first

  • Unplug a filter at the outlet before opening it, every time. Water and mains electricity is the one hazard on this site that has nothing to do with fish.
  • Never rinse biological media under a running tap, and never replace all of it in one session. Either can flatten an established colony within days.
  • A larger filter does not lower nitrate. Filtration produces nitrate; only water changes and plant growth remove it.
  • Packing a housing full of media until water struggles through it makes the filter worse, not better. Bacteria need flow past them.

What actually separates one from another

  • Rated gallons per hour is measured on a clean, empty unit. Real delivered flow is always lower once media is in and the intake has collected debris, so treat the box figure as a ceiling.
  • Whether the housing holds more than one piece of media, because that is what lets you stagger replacements and keep an established piece in place.
  • Where the outflow sits. A return that breaks the surface handles gas exchange for you and prevents most surface film problems.
  • Whether the impeller is a serviceable, replaceable part on that model. It is the component that wears and the one that causes most noise complaints.

Side by side

Filters — 2 products
ProductKey specBest for
Tetra Whisper IQ 130 GPH Power Filter130 GPH, up to 20 galA tank up to the 20 gallon figure the listing gives, where easy servicing matters.
Tetra Whisper 85 GPH Internal Filter85 GPH, up to 10 galSmall tanks, and any setup with no clearance behind the glass.

The products

  • Tetra Whisper IQ 130 GPH Power Filter

    Core pick

    Tetra Whisper IQ 130 GPH Power Filter

    130 GPH, up to 20 gal

    A hang-on-back power filter rated at 130 gallons per hour, listed for tanks up to 20 gallons in fresh or marine setups. Hang-on-back units keep the media outside the tank, which makes servicing straightforward and the outflow easy to aim at the surface. Remember that a rated flow figure is measured on a clean, empty unit.

    Why this badgeAt 130 GPH it is the higher-flow unit here, and turning water over is the job this category is for.

    The listing states this is a hang-on-back filter rated 130 GPH, for tanks up to 20 gallons, fresh or marine.

    Good

    • The 130 GPH rating gives useful turnover on the tank sizes it is listed for.
    • Hanging on the back keeps media accessible without reaching into the tank.
    • The return can be aimed to break the surface, which handles gas exchange and prevents surface film.
    • Listed for fresh or marine use, so it is not limited to one kind of setup.

    Watch out

    • Rated flow is a clean-unit ceiling; delivered flow falls as media loads and the intake collects debris.
    • Hang-on-back designs need a rim clearance the tank hood may not leave.
    • Cartridge-based media encourages replacing everything at once, which is the fastest way to damage a cycle.

    Best forA tank up to the 20 gallon figure the listing gives, where easy servicing matters.

    Check it on Amazon
  • Tetra Whisper 85 GPH Internal Filter

    Best for small tanks

    Tetra Whisper 85 GPH Internal Filter

    85 GPH, up to 10 gal

    An internal filter rated at 85 gallons per hour that clips inside the tank, listed for tanks up to 10 gallons. Internal units suit setups with no rim clearance and tanks that sit against a wall. Because the body is submerged, the outflow position needs a little thought to keep the surface moving.

    Why this badgeThe listing rates it for tanks up to 10 gallons, the smaller of the two size ratings in this category.

    The listing states this is an internal filter that clips on the tank, rated 85 GPH, for tanks up to 10 gallons.

    Good

    • Clips inside the tank, so it needs no clearance behind the aquarium.
    • The 85 GPH rating suits the small tanks the listing describes.
    • Nothing hangs over the back to interfere with a hood or a lid.
    • Submerged operation is generally quieter than a hang-on-back unit drawing air.

    Watch out

    • The body takes up space inside the tank, which is noticeable in a 10 gallon setup.
    • Servicing means reaching into the water rather than lifting a lid outside it.
    • A submerged outflow needs aiming deliberately if you want it to disturb the surface.

    Best forSmall tanks, and any setup with no clearance behind the glass.

    Check it on Amazon

Common questions

How much flow does my tank need?

A common planning figure is turning the tank volume over several times an hour, calculated as the filter's rated gallons per hour divided by the tank volume. Because the rating is a clean-unit ceiling, aiming above your target rather than exactly at it is sensible. What matters at least as much is that there are no dead spots where water barely moves.

Can I run two small filters instead of one large one?

Yes, and it has a real advantage: you can service one at a time and always leave an established colony untouched in the other. It also means a single failure does not stop all filtration at once.

The filter is running but the water is still cloudy. Is it too small?

Usually not. Cloudiness in a young tank is a bacterial bloom in the water column, not a particle load, and a bigger filter does not clear it any faster. Test ammonia and nitrite first — the readings tell you which problem you actually have.

How often should the filter be cleaned?

Clear the intake and squeeze the mechanical media weekly in tank water, rinse biological media gently about monthly, and open the housing for a deeper clean quarterly. Anything more aggressive than that costs you colony.

Where this comes up

Parameters this category touches