AhaBulbStuff Everyone Should Know
AhaBulb: Stuff Everyone Should Know · ahabulb.com/fish-undergravel-filter

In an under-gravel filter, what acts as the filter?

Start playing free

  1. A paper cartridge
  2. The glass walls
  3. The gravel itself

🔒 The answer is for AhaBulb members. Members see the answer, why it's right and the official sources for every card of Stuff Every Fish Owner Should Know, plus timed practice exams.

The first 50 cards of every test are free to play.

Play the free cards See membership

Like this card?
Play the game

References

  1. Merck Veterinary Manual (pet owner): Providing a Home for Fish www.merckvetmanual.com/all-other-pets/fish/providing-a-home-for-fish Checked 2026-10-11.

Think this answer is wrong? Tap "Challenge this answer" on the card in the game and tell us why.

Test yourself in the game

Fish & AquariumsWhat do beneficial bacteria turn ammonia into first?Fish & AquariumsWhat do nitrifying bacteria turn nitrite into?Fish & AquariumsWhat does cycling a new aquarium mean?

That's stuff everyone should know.