Bought a Rena 400 after researching this forum. Most claim it's been a good, quiet pump. Ordered from BigAls @ around $45.00 - expensive for an air pump. As soon as I pluged it in, I noticed it is not silent. I don't see how such a big pump could be, but after reading what some people have said about it, I was expecting too much. It sounds just like a big air pump. Ok, fair enough, no problem. Then, after less than 48 hours of running, it starts making this mechanical, resonating, high-pitched rattle. The only partial cure was too try to adjust the air flow such that it wouldn't resonate and make the rattle. In doing this, the best I could get was intermitent buzzing. So, I ordered a Tetra-Tec DW 96-2 for around $60.00 from Dr. Fosters & Smith. It's been running for a few hours now...no problems so far. As far as the normal sound of the pump, it sounds just like the Rena 400 - minus the buzzing of course. I did take the Rena 400 apart to see if anything stuck out as broken....nothing. Everything looks normal. I was so angry that I smashed it and put it in the garbage where it belongs. Many people will say it's a good pump and I must have gotten a lemon. My answer is if quality varies that much from pump to pump - and you will find others on this board that have had problems as well - then the manufacturing at Rena s****.
