boxtech Aquarium Air Pump,Oxygen Fish Air Pump with Adjustable Air Valve, Fish Tank Air Pump with Accessories Tube, Bubble Stone and Check Valve, Fish Tank Aerator Kit

quiet and small, the great part is you can change the flow of the stone, more or less water pressure.

Edit (6/1): The replacement double air pump is soooo much quieter, so it really was most likely just a batch issue. I really appreciate how accommodating and willing the seller was to send me another one, free of charge, because it had passed the window for me to do an exchange through Amazon. So despite all the trials and tribulations, I'm very satisfied with both the products I now have, and the customer service of the seller. Edit (5/29): After chatting with the seller about how noisy all three of my double pumps have become, they've agreed to send me a new double pump, as it may have just been a batch issue. So I've given another star based on their customer service, and once I receive the new pump I will update again based on how well it works. Edit (5/22): Originally, I rated these air pumps highly. I had one that was a little noisy, but it was tolerable. However, over time, it got extremely noisy, and when I finally had enough, it was just past the return/exchange date. I contacted Amazon and thankfully still got a refund, and I had planned to buy another since I thought one was just a dud. However, now all three are extremely noisy. I've tried different outlets, using longer tubing or shorting tubing, switching the order of control and check valves, putting the pump on the carpet floor, on the table, on the table with a mat... nothing helps. It's extremely aggravating and it affects my sleep. The only reason it gets two stars instead of one, is that the issue is only with the double air pumps. I have one of the single air pumps and it's been silent since I got it, and is still silent. Anyway, I'm very disappointed with how all three became so noisy. Original Review: I split my two ten-gallon tanks, so I could have 2 bettas per tank, while I left my one betta in her individual 5-gallon tank. So I bought three of these air pumps—two of the double air pumps and one of the single. One of the double air pumps, and the single air pump, are practically silent. I barely notice them. However, the other double air pump is extremely noisy, and it only quiets down when I really turn up the air flow, at which point it's too strong for my bettas. I've tried using both the control valves that came with the pump, as well as other valves that came with my new filters, but nothing helps, so it's a bit frustrating. Thankfully I'm not super sensitive to the noise, so I don't think it'll keep me awake or anything, but I do wish it was quieter. It's a bit strange since the other two pumps are quiet, so I don't know if I need to change how I set it up or if it's just defective, but I'll update if I'm able to get it quieter somehow.

This product does not fit Australian power outlets and they want you to send it back to get a refund (I threw it out) - DONT BUY!!

Dual output, small , does the job .

Much quieter than other big name air pumps that I have.