For the price, you really can't go wrong with this pump. Although only rated for a 40 gallon tank, I use a splitter to run 2 sponge filters in my 75 gallon tank and it has more than enough power to handle both filters. Originally, I purchased the 40 gallon pump to use as a source of power for my sponge filters in 3 10 gallon tanks. However, I found it to be extremely too powerful for the 10 gallon tanks. I keep three 10 gallon tanks side by side: fry, bettas along with a quarantine/hospital tank. The 40 gallon pump produced too much water flow for these sensitive little guys and I saw they were struggling more than they should when they're moving about. That's when I swapped out this 40g model to a 10g model and it has been working perfectly fine for the past year or so.

Now, I use the 40g model on two larger sponge filters in my 75g tank and that worked out as well. I don't understand the negative reviews of these Whisper pumps. They cost less than a bagel + a "vente" frappuccino at Starbucks...I'm not sure what people expect from them. I'll be more than satisfied if I get 2 years out of them. They run 24/7/365 for me and they are much more quieter than I had expected for an item at this price range. (The secret is to place the pumps on a carpet. If you only have a hard surface to place them on, cut an old sweatshirt and place the pump on the sweatshirt).

I got the Whisper 10 to replace the weak one that came with the small air-powered filter used with a 2.5 gallon Betta tank. I've had it for a little over a year. It definitely started out fairly quiet. However, I did experience what others report as an increase in volume over time. I saw someone note that it is one of the stationary magnets inside loosening and vibrating against something. That wasn't the case with mine. What I discovered is the rattle comes from the casing the pump sits in. The two sides of the case vibrating together. The screws that hold the two sides of the pump case are good, but the softer plastic material the screw post are set in seems to fatigue over time. If you try to tighten the case so there is zero rattle, by the time it is tight enough, the metal screw posts will actually start to pull out of the plastic, making it even looser and louder. The way I resolved this was by opening the pump casing by removing all the screws (while in there double checking all the magnet screws are tight), applying a strong epoxy to the rim where the case seals, then screwing it back together. Once the epoxy sets there is near zero noise, just the very low vibration of the motor inside, and no rattle at all. In fact, much quieter than it was new out-of-box. True, one can no longer open the pump to repair, but at $7 it is more or less disposable if the motor fails. In the meantime, I've had it operating for nearly a year with this mod, and still zero rattle. If it were not for this one flaw, I would have given it 5 stars, a very strong, sturdy little pump.

Worked great while it lasted. Almost to the day at the 4 month mark the pump got very loud. I took it apart and discovered the end opposite the motor has a rubber bushing and is held in place by a cylindrical piece of plastic which had cracked and broken into pieces. I bought some Gorilla Glue epoxy approx $5 or 55% the cost of a new air pump and repaired it. We'll see how long my repair last but I feel it should last longer than 4 months. Simply a design flaw.

I got the 100. It works GREAT very quiet, I have a bunch of the smaller ones 10's, 20's up to the 40 and I don't consider it any bit louder than they are. It provides great pressure and puts my airstones to full capacity with tiny bubbles coming out all over whereas the lower units only push out areas of the top and some mid section of the airstones with larger bubbles. Having only had the small units, I was surprised how large this 100 is and it's also nice to have two air outlets. I Will definitely buy 3-5 more of these for my fishroom to power sponge filters, it'll be nice to transition my noisier commercial air pumps to these nicer quiet ones

Purchased this to run a large sponge filter for a 10G plant tank that was previously powered by a junk Walmart brand 40-60 gal rated pump. That one died and was making all kinds of noise so I paid the money for this one thinking it would be much quieter! WRONG! This one is almost the same in terms of noise, plus every once in a while it will start making this loud (I want to call it grinding, but it's not since it's just an electromagnet) noise... You have to move it around or smack it to make it stop. It does however provide plenty of air for the sponge (it should, it's rated for 60 gallons in a 10G plant tank). You do have to follow the directions and use the included Y adapter to couple both outputs together into one or it doesn't seem to work correctly and is louder even still...