For the power of it and all that it seems superb. Only if my cabinet is open can you hear a very 'slight' hum. It is more or less silent. Ease of setup and the way it is all seperated into trays with lift out handles is fantastic. It woulld be 100% if it didn't have this problem. It is a major problem though, left it in the bucket over night, had aboout 5-10 litres in the bucket. This could be a really good way doing a water change, just empty the bucket out every 2 days...and add more...haha.