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How to Set Up a Whisper Tetra 40 Filter System

| Updated September 26, 2017

Things You'll Need

  • Bio bag

  • Charcoal filter

Tetra makes several products for home aquarium and pond systems. The Whisper 40i is designed for 20 to 40-gallon fish tanks, although it can also be used in turtle and amphibian tanks. The design of this filter includes a charcoal filter and bio bag that filters the water. No matter the tank you use this filter in, the set up is the same and takes only a few minutes.

Hang the filter on the back of the tank. The filter should be inside the tank and hung with the attached hanger. The electrical cord should be outside the tank and not in the water. Push on the base of the filter gently at the level of the suction cup to get the suction cup to adhere to the glass and keep the filter stable.

Place the bio bag, which is the white bag, in the slot at the back of the filter. There’s no front or back to the bio bag, but do put the bag in right side up.

Place the charcoal filter in the slot towards the front of the filter. The charcoal filter will say “front” on the side that should face into the aquarium.

Fill the tank water so that, at a minimum, it rises above the intake at the bottom of the filter. The intake is the row of vertical slots at the base of the filter. If the water does not cover the intake, the filter will not function properly. If you cannot fill the tank full enough to reach the filter, then lower the filter by adjusting the hanger, but keep it at least one inch above the substrate in the tank.

Fill the filter with water. This will help it start properly when you turn it on.

Plug in the filter. This will start the filter. If the filter is not starting, put some more water inside the filter.


  • Do not put plants, rocks or other tank décor too close to the filter. If the filter is not taking in water, try moving objects and plants further away from the filter intake.