Hi everyone! Recently bought a new fish tank which is 93litres (20.45 gallons) and I'm keeping tropical fish. I have a silver molly and black molly in there at the moment. My tank came with 100g activated carbon+anti-nitrate resin in a net bag, 500g bio ceramic rings in a net bag, white filter foam and blue filter foam which all makes up the filter system. I have installed this into the side box in my tank along with a heater. My tank came with a water pump which was pumping water into my tank but I didn't understand how to work the pump properly and my mollies seemed to be gasping at the surface (I think), I then got rid of this water pump and switched to an air pump with an air stone and my mollies seem to not gasp at the surface much at all. My issue is the air pump is loud! I've tried tetra and other brands but I hate the noise. Do you think I should switch back to the water pump because it was less noisy or do I not need a pump at all? Sorry, I'm new to this and just want to make sure I'm doing everything right! Thank you all.