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💧 Keep it clean, keep it quiet — your aquarium’s new best friend.
The Tetra Whisper 40i Internal Filter is a compact, submersible filtration system designed for 20-40 gallon aquariums. Combining a quiet air pump with a 3-stage filtration process, it filters up to 170 gallons per hour while oxygenating water. Its internal mounting clip allows tanks to sit flush against walls, and the easy-to-replace Bio-Bag cartridges trap debris and fish waste efficiently. Trusted by hobbyists for decades, it delivers reliable, low-maintenance performance that keeps aquatic environments pristine and peaceful.

| Customer Reviews | 4.3 out of 5 stars 22,282 Reviews |
T**R
Love, Love This Filter!
Okay so... I have a 20 gallon temporarily for my 4 inch turtle. I accidentally bought the smallest of this tetra filter, so I bought the medium sized one in it's place. I had only had the tank filled halfway anyway since my turtle was only 1.5 inches at this point. Mind you I didn't realize how fast they grow, and had no idea that Its recommended to have a filter that can filter 2 to 3x the tank size. So I decided to keep both filters in my tank. One on each side. Even though I still don't reach the recommended filter size, my water now almost filled to the top, stays absolutely clean. Turtles are pretty messy so I still have to do the weekly cleanings and all that extra stuff that apparently those who spend hundreds of dollars on filters still have to do as well. I don't know if this is some kind of luck thing, I don't know if maybe my turtle just isn't that dirty (yea right, I see him)... but I'm actually not looking forward to switching out my filter for the 'recommended' filter size, as these filters work so good. I love them. They are both very quiet. Aside from the sound of the water falling back in.. I mean it sounds like a waterfall. Who doesn't want to hear a waterfall? I love it. This can also be prevented by raising the water level or lowering the filter itself. Basically the closer it is to the water, the quieter it is. Such a simple device, yet so beautifully sufficient. The little one stopped working at one point and I thought... welp there you go! Get what you pay for. But nope! Removed the base, pulled out the magnetic spring propeller and tube, cleaned it out and like magic it started right up as soon as I plugged it back in. Love how easy it is to replace the filters. The filters themselves are great and definitely hold on to some dirtiness. One thing I'll say is there is quite a bit of unused empty space. I now take advantage by adding some extra media, but I must say that these filters work great even without the extra. Love this filter and would recommend above any other filter.
J**E
👍🏼
This fish tank filter has been a solid addition to my aquarium setup. It keeps the water clear and clean, and I’ve noticed a big improvement in overall water quality since using it. It runs consistently without much maintenance and helps maintain a healthy environment for the fish. It’s easy to set up and doesn’t require anything complicated to get started. The flow is steady and helps with circulation without being too strong for the tank. Cleaning it is simple as well, which makes routine maintenance much easier. Overall, it’s a reliable, effective filter that does its job well and helps keep the tank balanced and healthy with minimal effort.
E**G
Big improvement
Big Improvement over the previous model. My small tank came with the previous version of this filter and it has a quite significant design flaw that twice caused the unattended tank to lose almost half it's water. Essentially, if the filter was at all clogged with particulate, water pressure would cause the water level in the filter to rise to the point it would flow out of the tank on the clip holding the filter to the edge of the tank. After the second time this happened and a lot of luck that it didn't fry my power strip, I decided it was time to switch filters. While I was prepared to move totally away from Tetra due to my upset over the previous situation, I noticed while researching the change in holding clip. The new design obviously is in reaction to the problem I encountered as it now is architected that even if water were to move back onto the holding clip, it would drain down into the tank as the attackment to the wall is lower on the body. Since I pretty much liked everything else about the design, I decided to give the new version a try. Price-wise it was reasonable and the noise level is very low. Once I received it, it was easy to assemble. My one complaint would be that the box contained two suction cups, but there is no instruction on how they are to be used. That said, I was able to position the filter very easily and the updated design allows it to be placed in such a way that it doesnt interfere with the tank cover. That had been a big complaint I had about the previous design. It was very quick to assemble, get in place, and start using and the speed of the water flow seems appropriate for the smaller tank size. Cleaning is easy since it essentially is just replacing the filter periodically. They do recommend on a yearly basis cleaning the impeller, which should help it last longer.
T**Y
Quiet and effective
I have a 5.5 gallon tank and its works great but obviously will need to change water more often cause its not meant for that size but I have a betta and they dont like alot of water movement so this gentle flow is perfect for her. Also very quiet. When im in the room I dont even notice the sound unless im legit paying attention to it. I noticed when I first installed it was loud but thats because it was not placed correctly so if yours is loud adjust the placement of the filter. Also keep in mind the sound on the video as my phone catches every little sound when I record so its louder in the video then in person. The sound is equivalent to a soft hum
O**E
Tetra Whisper Internal Filter 10 To 30 Gallons is a great product!
Great product! I ordered 4 of these the past few months and the last one I ordered came without a hanging bracket and suction cups. However, I reached out to Tetra and they were kind enough to send me a replacement. This product works great and the Tetra's customer service is excellent.
L**T
!!PLEASE READ!! DO NOT BUY FOR SMALL FISH
I recently set my smaller fish tank back up to put some fish out of my main tank into (tank full of guppies and a couple algae eaters) as one of the “algae eaters” has begun to jump through the water and swallow my guppies whole. I had the filter left over from a goldfish I had for a few years in there and figured it would be fine. When i moved the fish into said smaller tank i moved six over and then a smaller one ended up popping up (making it seven fish) i went to sleep and all were fine. When i woke up i noticed one of the fish i had put in there had died, the next day (today) FOUR MORE were missing when i woke up. Two had gotten tangled in a fake plant and died (i figured it was fault for putting it in with the guppies) i then watched one of two remaining fish be blown into said plant by this filter as i was investigating. I saved that fish but it was somewhat weak (i was actively treating the tank for ick) so i let it be. i CAME BACK ABOUT FIFTEEN MINUTES LATER TO ONE FISH. i figured it had went into the little structure i have in my tank, it had in-fact not. Instead i found it another fifteen minutes later when i saw something peeking out of the bottom of my filtration system. It was the tail of A DIFFERENT FISH that i figured had passed in the fake weeds. Upon seeing this i pulled the filter and was appalled to see MY LAST FEW FISH I COULDNT FIND HAD BEEN EATEN BY THE FILTER. Two of them were dead- i then had a half paralyzed fish that died about 30 mins later. Ive now unplugged the filter with ONE OF SEVEN FISH LEFT AFTER A DAY AND A HALF OF USE. I Strongly advise against getting this filter if you have guppies as it may cause a quite disturbing scene. ALTHOUGH this filter killed a bunch of my guppies (literally sucks so hard it ate them) it WORKED GREAT FOR MY FULLY GROWN GOLDFISH for about a year before he passed so that is something to take into account. Personally i think it should be advertised that this filter CANNOT HANDLE SMALL FISH NO MATTER THE TANK SIZE.
R**L
How can something so simple work so well?
When you open the box, the Whisper 40i (or it's smaller siblings) don't seem very impressive. It's not much more than a oval plastic bucket, with another bucket (containing a motor and pump) snapped onto the bottom. If you looked at one and thought "this can't possibly work", you would be so wrong. Perhaps they work as well as they do BECAUSE they are so simple, and so have little chance for things to break. The pump sits IN your aquarium water, so it never needs to be primed. You plug it in, and it begins working, filling the upper bucket, where the water flows through the filter pad and spills back into the aquarium. No priming necessary ever, including after a power failure. When the power comes back on, it just starts working again. It's a shame that every hang-on-the back power filter can't make a similar claim, some unfortunately will lose their prime and/or fail to restart, resulting in unhappy fish and sometimes a damaged filter. There are no adjustments for flow, so these only run at one flow rate. Inevitably, some food can get sucked up if you let it run while feeding. I have the filters on a separate power strip, so when I feed my fish, I just use the switch on the power strip to turn the filters off for an hour or so. Easy solution and prevents the filter pads from clogging so quickly. There is no top or lid (unless you buy the model intended for reptiles), so the filter pads just sit there exposed. This means that the water in the filter is fully aerated as it passes through the pads. It also means that no other internal filter is as easy to change pads when they become clogged. The top edge of the pad is above the water line, so you just grab it with two fingers and lift it out. You don't have to disturb the suction cups or hanging bracket at all. You don't have to put your whole arm down into the tank. Maintenance which is easily performed is more likely to be done when needed, so easily changed pads are more likely to be changed when clogged. You have options for how you want to attach the filter. The box includes two suction cups, and a newly designed bracket which hangs over the edge of your tank. I use the bracket, as it's adjustable for height and I don't have to worry about suction cups losing their suction. The filter pads are the Whisper bio-bags, which amount to a thick fluffy poly bag, over a plastic frame, with carbon granules inside. Replacing these is simple, and if purchased in a 12 pack from Amazon, cost about 60 cents per bag. I used Emperor filters for years, and in my experience, these bio-bags work a lot better than the filter cartridges for Marineland products and cost much less to buy. If you rinse them under tap water, which is easily done, the cost is even less. Rinsing the bags doesn't disturb your biological bacteria since they are on a separate part (resembling a hair brush) which remains in the filter when you remove the bags. You do have some flexibility with regard to media options as well. You don't have to use the carbon which is included with the new pads. You can put anything you want inside the bag, and if desired, transfer it to the new bag next time you change them out. You also don't have to use the separate biological "hairbrush", and if you leave it out, you have room to put another media bag in it's place, with ceramic rings, or whatever else you can think of. I have four of these, mounted on two separate tanks, one 55 gallons, the other 75 gallons. All four of them are not quite silent, but very quiet. There is a soft, low hum from the motor windings, a little bit like a transformer humming. At first there was also a faint sound like air trapped somewhere, perhaps cavitation in the pump? But these sounds are hard to hear, and not distracting. And the cavitation sound went away on it's own after a few days. I can hear the soft humming sound if the room is totally quiet and I stand near the tank, but if there is any significant sound from conversation, crunching breakfast cereal, a radio or TV, etc, then they are drowned out. Some of the complaints others have mentioned in their reviews sound a bit like operator error to me. For example, one person said the filter overflowed and sent water over the back of the tank onto the floor. Clearly, the filter was mounted too high....mine are mounted with the top edge 2 inches below the rim of the tank. When the filter pad becomes clogged, it WILL overflow, but into the tank, not out of it. Some describe loud mechanical noises, which sounds to me like a bit of gravel, or perhaps a snail, found it's way into the pump impeller. Yes, this can happen with any filter, regardless of brand, but it's easy to repair. In these filters, the bottom just snaps off, exposing the pump impeller, which is then easily removed for cleaning. And some have complained that the filter "stops working" after some months of service. Again, this is likely due to a need for a cleaning of the impeller and the recess where it sits, where debris or gunk sometimes builds up and prevents it from rotating. On a benefit/cost basis, these filters look really good. They are made of a tough, slightly flexible plastic, so even if you drop one on the floor, it is unlikely to break. Parts for Tetra/Whisper filters are readily available everywhere. And the results are as good as any other filter I've ever used, regardless of cost. The first attached photo shows two mounted in my 75 gallon planted tank, which contains two Nigerian bichers, and two Pictus catfish. The second shows two more in my 55 gallon community tank, with various tetras, cory catfish, and loaches.
Y**W
works ok
This filter works well for a turtle/fish tank and performs great in daily use. When the water level is high, it runs very quietly, which is a big plus. Filtration has been effective overall. That said, it becomes quite noisy when the water level is low, so regular monitoring is needed. I’ve also purchased two of these, and both stopped working after about a year. Still, because it works well while it lasts, I’m giving it four stars.
J**S
Tiene buena calidad
Silencioso y mantiene la pecera limpia
D**N
110 فولت 😔
للاسف المنتج 110 فولت ولايوجد في الوصف تحديد للجهاز،وعندنا في السعودية 220 فولت فقط،بالاضافة الى ان غطاء الفلتر غير ثابت،لابد من ارجاع المنتج
P**.
Excelente producto
Los pocos días que lleva en uso a sido 100% efectivo, limpio el agua de mi pecera a pesar que ya estaba un poco sucia. Súper silencioso y de buen tamaño Hasta ahora todo bien
S**T
Piece of junk
Plugged it in and it was dead. Waste of time and money, spend it elsewhere. Now I’m left with extra filters that I purchased and a dead pump/filter. Not happy Jan.
S**O
Great filter, very quiet.
I have the 10-30 version too in another tank. This bigger one is a bit louder but it's still very very quiet. These are the best filters for noise levels. I put my own bio media and filter floss in as I have a planted tank. Works fantastic.
Trustpilot
3 weeks ago
2 weeks ago