I ordered the Tetra 40 gallon pump after reading a lot of the reviews. There were a lot of pros and cons on the amount of noise it made or did not make. I hooked mine up and immdiately noticed an unacceptably loud humming noise coming from the pump. The humming was so loud I could hear it down the hallway and from adjoining rooms. I let it run for about 48 hours hoping the noise would tone down after it was broken in which did not happen. The good news is that Amazon is crediting my account after I sent them an email. This is the first of many things I have ordered from Amazon and the only one where I had a problem and had to request a refund. I don't know if I just got a defective pump or what. I will say Amazon's price was the best I found. Shopping locally I found the same pump in pet stores was selling for over twice what I paid at Amazon.