Tetra Whisper 85 GPH Internal Power Filter

The Tetra Whisper 85 GPH Internal Power Filter is a small filter that clips inside the tank. It’s sized for 5 to 10 gallon aquariums and uses medium Whisper Bio-Bag cartridges. Water runs through the floss, which catches debris, and past activated carbon, which helps clear odor and discoloration.

Two sizes

This page also covers the 135 GPH model, which is rated for 10 to 30 gallon tanks and takes large Bio-Bag cartridges instead of medium. Both work the same way. Pick the one that matches your tank, and remember which cartridge size it needs. For 20 to 40 gallons, see the Tetra Whisper 170 GPH internal filter.

Where it makes sense

• Tanks close to the wall. It sits inside, so Tetra says the tank can be about an inch from the wall.
• Low water levels. The adjustable clip lets you set it high or low, which suits turtle tanks and partly filled setups.
• Hidden filtration. It tucks behind plants or decor.

Cartridge care

Bio-Bag cartridges hold some of your beneficial bacteria. Rinse a dirty one in old tank water rather than replacing it early, and avoid changing it on the same day you deep-clean the gravel. Our page on Whisper Bio-Bag cartridges covers sizing and swap timing.

Small tank cautions

In a 5 gallon tank, even modest flow can push bettas and tiny fish around. Aim the outflow at the glass, or add a sponge over the intake if you keep shrimp or fry.

Who should look elsewhere

Keepers who want more media space or quieter running in a small tank might prefer a slim hang-on or a sponge filter. Tetra lists a two-year limited warranty on the 85 GPH model.