Tetra Whisper Air Pumps & Filters Guide: Sizing by Gallon

Filtration and aeration solve two different problems, even though beginners often lump them into one “equipment” purchase. A filter processes waste, mechanically, chemically, and biologically.

An air pump moves oxygen into the water and helps push off dissolved CO2. A tank can run a filter with no air pump at all and be fine; it can never run an air pump instead of a filter and be fine.

This guide covers sizing both correctly for your tank, and where Tetra Whisper fits across power filters, internal filters, and air pumps. For filtration media and mechanics in general, see our complete filtration systems guide.

Sizing a Filter: The GPH Rule of Thumb

Filter output is rated in gallons per hour (GPH), and the standard target is turning over the entire tank volume four to six times per hour.

A 20-gallon tank wants a filter rated somewhere around 80 to 120 GPH; a heavily stocked tank or one with large, messy fish should sit at the higher end of that range, not the lower one.

Manufacturer gallon ratings on the box are a starting point, not a guarantee, since actual flow drops as filter media loads up with debris between cleanings. Sizing up rather than sizing exactly to the tank gives you headroom for that natural decline.

Tetra Whisper IQ Power Filter: Hang-on-Back Sizing

The Whisper IQ line is Tetra’s hang-on-back (HOB) power filter, self-priming so it starts moving water on its own after a power outage instead of needing to be manually restarted.

It’s the most common filter format for tanks from about 10 to 55 gallons, and Tetra sizes the IQ models directly to gallon ranges rather than leaving you to convert GPH yourself.

Tank size	Whisper IQ model
Up to 10 gallons	IQ 10
10 to 20 gallons	IQ 20
20 to 30 gallons	IQ 30
30 to 45 gallons	IQ 45
45 to 60 gallons	IQ 60

If your tank sits right on a boundary, size up rather than down, a filter running comfortably under its rated capacity lasts longer between cleanings than one working at its limit.

Tetra Whisper Internal Filter: Small Tanks and Quarantine Setups

The Whisper Internal filter submerges fully in the tank rather than hanging on the back edge, which makes it the better fit for nano tanks, quarantine or hospital tanks that need to be moved around, or setups where an HOB filter’s footprint just doesn’t fit the rim.

It trades some flow capacity for that flexibility, so it’s best suited to smaller volumes, generally under 20 gallons, rather than as the primary filter on a larger community tank.

Tetra Whisper Air Pumps: Sizing by Gallon, Not by Filter

Air pumps power air stones, bubble walls, and sponge filters, and they’re rated separately from your power filter entirely; an HOB filter running well doesn’t mean you don’t need one, since surface agitation from an air stone adds gas exchange a filter’s output alone often doesn’t fully cover, especially in a heavily stocked or heavily planted tank at night when plants stop producing oxygen.

Tank size	Whisper air pump model
Up to 10 gallons	Whisper 10
10 to 30 gallons	Whisper 30
30 to 60 gallons	Whisper 60
60 to 100 gallons	Whisper 100

Running a sponge filter off one of these pumps is also the gentlest filtration option for a fry tank or shrimp tank, since it moves water without the intake risk a power filter’s impeller carries.

Do You Need Both a Filter and an Air Pump?

Most standard community tanks running an HOB filter get enough surface agitation from the filter’s own output and don’t strictly need a separate air pump.

Where an air pump earns its place is sponge-filtered tanks, heavily stocked tanks, overnight oxygen dips in planted setups, and anywhere you want bubbles for their own sake. For water-pump specific sizing, our aquarium water pump guide and our hang-on-back filter comparison go further into equipment beyond the Tetra lineup specifically.

Size the filter to turnover, size the air pump to gallons, and treat them as two separate jobs rather than one combined equipment purchase. For the rest of the Tetra lineup, see the full Tetra products guide.

Frequently Asked Questions