Hi,
What type (looking for quiet one) of air pump is good for 33GL ?
Thank you very much for your advice.
I use tetra whisper pumps, they work great and not to noisy.
As stated, Tetra Whisper (gets a lot of recommendations on the net). I own a smaller one, and it's fine but I don't run it since I got plants.
You can try the foam pillow trick, or suspending the pump to further reduce sound.
Of course bubbles themselves can make quite a bit of sound.