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Rated 3.6 out of 5 by 113 reviewers.
Rated 5 out of 5 by Small Heater for Small Tanks Locating an aquarium heater for a tank less than 10 gallons is no easy task; the majority of heaters aren’t designed for smaller aquariums despite their continued popularity. I chose the Tetra Whisper Heater 2-15 gallon model for a few reasons; 1) I’ve used Tetra products over 25 years, 2) Its compact size of 4.75”. There is no thermostat; the heater is designed to maintain the water temperature between 76-80 degrees. I have monitored the temperature in my 5 gallon Mini Bow over several days, the temperature has evened out to 79 degrees. It is safe for acrylic tanks (I checked before purchasing), is completely submersible with the option of vertical or horizontal positions and contains a indicator light to let you know its working. I am quite pleased with this little heater and I’m sure my Betta (Indiana Jones) is thankful he won’t be subjected to temperature fluctuates that could lead to illness. 11/02/2008
Rated 5 out of 5 by Great product I have used 2 of these heaters for the past 3 years and they have both been great. The heater does a good job of keeping up the temperature. I know this for a fact because my fish have been healthy and have lived long lives. I also own a crayfish and it has molted which is a good sign that the water is at the right temperature. Many people are reporting that it does not raise the water temperature to what they want, but that is probably because they are checking the temperature of the glass on the outside. You should dip your finger in to see if it's warm to decide because the glass will always be cooler than the water. This heater also has a small red light that glows when it's heating the water and it turns off when the water has maintained the right temperature, so don't take it as being broken. If you want to check to see if it's still working, place it in a cold bowl of water and plug it in. If it works, the red light should glow. 08/31/2010
Rated 3 out of 5 by Proper prep not in instructions! Like a few reviewers, I've had issues with this heater. I came back to read the reviews and I realized that in the directions nowhere does it say you should let the heater acclimate to the water before turning it on. I unplugged it for 30 minutes (while submerged in water of course) then plugged it back in, and within an hour the water in my 10 gallon tank was reading 76*. So if you have this problem try unplugging it and letting it sit for a bit before turning it back on. 01/27/2014
Rated 4 out of 5 by good little heater I got this to put in a 6 gallon tank. It keeps the tank at a steady temperature of 76. Overall, I am pleased with the product. 04/29/2009
Rated 5 out of 5 by great product! love this water heater! it works great! we have a large tank and it's filled half way with water. about 50 gallon. it works well with our tank. we first got this water heater in 2007 (fall) so really it does last . it's automatic and even our new cichlids loves the water. they just breed and the fry are so adorable!! we placed our water heater near the flitter. Our cichild spwan their eggs near the now that's their territory. you can't beat the price for such a good h20 heater! ***As you can see in the picture, our two cichlids are near the waterheater protecting their fry*** 03/30/2009
Rated 5 out of 5 by Does what it says It keeps the tank at 78 degrees plus or minus 2 degrees, doesn't take up much space, little red light says its heating, suction cup works nicely, unplugged now it's summer though 06/03/2013
Rated 5 out of 5 by GET IT! This heater is great for my 2.5 gallon Betta tank. it keeps my tank between 78-81* its wonderful, and my female loves to sleep on it :)~ its tough and dependable - love it! 12/20/2010
Rated 1 out of 5 by Doesn't Heat Water Properly I breed fish and some of the tropical species need the warmer waters in the high 70's to low 80's. I purchased this one because it seemed like a good value. The heater says it heats up to a 15 gallon tank to a constant temperature of 78 degrees. Unfortunately that is not the case. I had it in a 10 gallon tank for an entire week and it never heated the water more than 74 degrees. The last straw was when it let the temperature fall to 72 degrees. 4-6 degrees doesn't sound like a big deal but for fish it's a deal breaker. For the same price I found one at pet store that you can manually change the temperature on. For the beginning owner that just wants to keep a couple hardier species of fish this product MIGHT be okay. But for anyone that really wants their fish to thrive I'd pass on this one. If I pay for a product that says it heats to 78 degrees then that's what I expect. Very disappointing product. 04/22/2013
Rated 1 out of 5 by Frustrated! I purchased this heater through Walmart 2xs. The first one lasted two days. The second one lasted one day. The directions say "submerge in water, then plug in." That's what I did. The box and directions both say that the heater will maintain the tank temperture at 78 degrees. The first heater I had brought the water temp to 74 and the second made it to 70. Now my fish are cold once again. On the plus side, I really like the overall appearance of this heater. It is small and blends into the background (that would be why I purchased it the second time). If you buy this item, I hope you have better luck! (Oh, my tank is 10 gallons. So, if you have a smaller tank, maybe it will work better.) 01/25/2011
Rated 5 out of 5 by Warmth Is Good Living in the mountains, with varying heat/cold, our Betta needed a constant temperature. This heater is keeping the new 5 gal. plastic tank between 75-79 degrees. Its nice to have the light going on and off to know that its working. Azul is more active and happy! 11/08/2010
Rated 5 out of 5 by The best Betta heater ever! My Betta has never been happier since getting this heater! Someone said that the directions were not proper and that the heater needs to be acclimated to the water? That's not true. Think about it: It's not in the instructions because it's not necessary!! Just put the heater in the tank wherever you want it, plug it in, and it works. It keeps the water perfectly warm for my Betta. 03/20/2014
Rated 1 out of 5 Just Doesn't Work I figured since this product said it would heat aquariums up to 15 gallons that it would easily maintain a decent temperature for my 5 gallon tank. Before buying this heater I knew that at night the water temperature of my tank dropped to 69/70 degrees F. During the day with the small hood light on it would raise to 74 degrees. Right now I only have live plants and no fish. After submerging the heater for 30 minutes I plugged it in and it showed a red light indicating the heater was on. I noticed 10 minutes later that the light was off. So I unplugged it and let it sit for a few minutes then plugged it back in. The light would come on for only a few minutes before turning off. Several days later the temperature of the water was the exact same as before I even bought the heater. I thought it was broken, but after having it for almost 2 weeks now I found that the heater only comes on at night when the temperature drops to less than 70 degrees. Once the temp. gets to 70/71 degrees it turns off. Which really does no good at all. I even tried moving the heater next to the filter so there would be water flow in hopes it would keep the heater on but it didn't help. Buying this heater was a waste of money and time. Unfortunately assuming this product would work the way it was described I threw away the receipt and lost out on 15$ I could use on a reliable heater. 02/25/2013
Rated 4 out of 5 by Awsome This product does his job quite well. It maintains well it's temperature watever is your room temperature. It is great in that way. The only negative of it is that you can't control the temperature and you need to put it at at least 30 degree celcius to cure some illness (for fishes). So i had to buy an other heater to cure my fishes. But that heater maintains way more the temperature than the one i can contorl it though, which is why i still keep it and use it =] 03/17/2009
Rated 5 out of 5 by Tetra Heater for Aquarium 5-15 gallon I got the heater and installed it. I love it. It is perfect for the aquarium and for the price, it can't be beat. You can install it either upright or horizontally in the tank. it is small enough that you can't see it. It is not in the way at all and keeps a perfect 78 degrees Temp for my beta fish. Bubbles is very happy! 07/14/2012
Rated 1 out of 5 by Does not heat well I purchased this heater for my little Betta fish to heat her 3 gallon tank. I had high hopes for this heater as it stated on the package it would heat up to 78 degrees however it does not get above 72. I now have a cold lethargic Betta on my hands and am returning this one as soon as the other heater arrives from ebay. Please don't waste your money here folks. You will be disappointed :( 09/23/2013
Rated 1 out of 5 by Not that great... I have a ten gallon tank, and the heater keeps it at about 72 degrees, when it should be 78. I am very disappointed. The little red light that indicates it is heating turns off all the time when it hasn't even reached it's specified temperature. I am planning on investing in a better heater. 01/28/2010
Rated 5 out of 5 by Purchased this for a 10 gallon tank I purchased this heater for my 10 gallon fish tank i just purchased yesterday. I noticed the lighting in the hood above the tank kept the water somewhat warm, but i decided to purchase a heater to make sure the water maintained the adequate level of heat throughout the entire tank for the fish i intend to purchase. When i first installed it, i waited 20 mins then plugged it in. The little red light never came on and the warmth of the water stayed the same over the next couple of hours. I instinctively thought i bought a defective item. Since the water in the tank was already warm, i tried getting a glass of ice water, submerging the heater and waiting 20 minutes. When i plugged it in the little red light came on and within a couple minutes the ice began to melt and the water started heating up. I turned off the light to my fish tank and re-installed the heater. After another 20 minutes i plugged the heater back in and the red light came on for a few minutes and then went off. The water has since maintained its warmth and i have turned the light back on under the hood of the fish tank. I have not seen the red light on the thermometer pop back on yet, but the water is warm. I will be purchasing thermometers in the morning and observing the consistency of the temperatures for a few more days before i purchase any fish. 03/29/2013
Rated 3 out of 5 by Doesn't seem to be keeping the temperature at 78 I bought this heater for my 2 gallon tank. It's supposed to keep the tank at 78 degrees but the tank has stayed at a pretty constant 76. This heater is recommended for tanks 2 through, I believe, 15 gallons so I'm surprised it isn't keeping the right temperature on such a small tank. The onlly thing I can think of is the thermometer I'm using is one that is placed on the outside of the tank so perhaps it just isn't giving an accurate reading. 12/31/2013
Rated 4 out of 5 by great water heater in winter for out door pets I have cats living in our garage year round and this heater will keep the drinking water from freezing. I have had it for three years now and need to replace it. This heater is well worth the price and the cats are greatful for it. 02/13/2012
Rated 4 out of 5 by Keeps a steady 76... on my out-of-the-tank sticker-thermometer. There's not much more I need to add that would differ from the previous reviewers thoughts. It's a great little heater for my 5 gallon tank that only has one tropical fish in it. And the fish is happy. I don't think you can go wrong with this heater. It has a suction cup that sticks quite well to the acrylic tank and hasn't moved since I installed it approximately 3 months ago. I do think it should've been less than ten dollars, but it was just under 15 in the store. 11/21/2008
Rated 5 out of 5 by Great heater for a 10 gallon tank I have a ten gallon tank and put it in the heater and in a little less than 24 hours it was at 72-73 degrees. I went to buy the fish and they seem to be very happy now. They are gouramis, platies, and swordtails so they prefer a temperature of 72-82 degrees. Our house can sometimes get pretty cold and the heater was still at optimal temperature. 01/16/2012
Rated 5 out of 5 by It works Red LED indicating it is working. Water temp seems to be about right. Never seen green LED light though. 01/19/2016
Rated 5 out of 5 by Keeps my tank at 76 degrees all the time I have used it on a 3 gallon and 5 gallon and it works to keep water between 76 to 78 degrees. Does a good job. Does what it says. I have no complaints. 07/15/2014
Rated 5 out of 5 Excellent Product! I purchased this aquarium heater for my previously small 2.65 gallon tank with success and no complaints. When I then upgraded to a 10 gallon tank and again, placed this heater in, it did not let me down. I have had to numerously unplug it and it has also gone through various power outages, etc., and I can honestly say that this heater has proven itself very worthy of my excellent review. A 'must have' for any aquarium of 2-15 gallons I am sure of, as the price is right. 06/29/2013
Rated 5 out of 5 by Heater for 10 gallon salt water aquarium This is an excellent heater, great price and outstanding quality. It arrived before the stated date, and I am very happy with my purchase. I can highly recommend this item. 12/29/2012
Rated 4 out of 5 by Great Heater I was leery of this because of some reviews but it works well. The only draw back is it is not adjustable, and the price is too high for a low watt heater. I got a heater twice the size for 4 dollars more, but online. Tetra makes great products for fish keepers on a budget, but this heater could be 10 dollars since it only heats tanks 5-15 g. But it does have an indicator light (unlike even expensive heaters) and keeps the water very even. The compact casing does wonders to keep it safe, but the packaging NEEDS to be adjusted. the case is open to break right in the store, and I have found some broken. I mean there is not even plastic between the box and the heater. So pick out one carefully. If it adjusted and was less expensive it's would be a killer heater. Very good for anyone looking for a betta, or smaller 10 g heater. 10/04/2012
Rated 5 out of 5 by Excellent Product, Great Value!!! I purchased this heater at my local Wal*Mart for my 5 gallon aquarium. This heater works great and keeps my aquarium around 78 degrees Fahrenheit (76-79F). The price is excellent and I love the size, not to big and not to small. It is easy to hide in an aquarium and if placed horizontally above the gravel, makes it practically disappear into the landscape of the aquarium! For only $15, this heater is a great investment in the health of my aquarium and its inhabitants! 10/30/2010
Rated 1 out of 5 by BE CAREFUL! I purchased this heater for my 10gallon tank. It worked the first day and then I went on a business trip for a week. I came home to a 50* tank and $20 in dead fish =( I took the heater back to walmart and they replaced it for another one. The heater worked for 10 days and the tank is again 52* as I'm typing this. I will not risk my remaining fish a third time and certainly wont trust a walmart heater with them =( It worked fine the 10 days it worked, but I expect more from a purchase than 1 day or 10 days lifespan. 11/06/2012
Rated 4 out of 5 by Decent Heater I bought this heater for a 3 gallon aquarium. It keeps my tank at a constant 76 degrees, so it doesn't quite get the tank to the 78 degrees advertised. This is just fine for a small tank, but I would buy a larger heater for a 10-15 gallon tank. 02/24/2012
Rated 5 out of 5 by tetra heater 2-15 gal. this little heater is awesome. it's great for my small tank that i have frogs in. it sure is a life saver. i only have wood heat and sometimes the house isn't very warm so at least my frogs can be warm. 03/03/2009
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