Tetra Whisper Bio-Bag Filter Cartridges

Tetra Whisper Bio-Bag cartridges are the replacement filter inserts for Tetra Whisper filters. Each one is a dense, dual-sided mesh bag filled with activated carbon. The mesh catches debris and fish waste, while the carbon removes odors and the yellow tint that builds up in aquarium water over time.

Picking the right size

Whisper filters take different cartridge sizes, and Tetra color codes the packages so you can remember which one your filter uses. This page covers the medium cartridges in a 3-count pack, which suit smaller Whisper models. The large cartridges are also sold unassembled in a 12-count pack for bigger Whisper filters, such as the Tetra Whisper IQ. Check your filter’s manual or the old cartridge before you order.

How often to change them

Tetra suggests changing the cartridge monthly, or sooner if it clogs. Carbon stops absorbing once its pores fill, and a packed bag slows the flow through the filter. If you notice the water turning yellow or the outflow weakening, it’s time.

Protecting your biofilter

Beneficial bacteria live on the cartridge too. If you throw out the old bag every month, you throw out some of those bacteria. A few habits help:

• Rinse a dirty cartridge in old tank water to stretch it a week or two, instead of swapping early.
• If your filter has a separate bio-grid or sponge, leave it alone when you change the bag.
• Don’t change the cartridge on the same day as a big water change or gravel clean.

Assembled or unassembled

The medium 3-count cartridges come fully assembled and ready to drop in. The 12-count large pack is unassembled, so you fit the bags onto frames yourself, which costs less per cartridge if you keep several tanks.

Who should look elsewhere

If you’d rather stop buying cartridges, filters with refillable baskets let you use bulk media. A hang-on like the AquaClear 110 takes loose foam, carbon and bio media.