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Fluval

Fluval M 100-Watt Submersible Aquarium Heater – Compact, High-Performance, Reliable Heating For Fresh & Saltwater Tanks

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Availability: In Stock.
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Arrives Feb 17 – Feb 18
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Size: M100


Features

  • Powerful & Reliable Heating: The Fluval M 100 Watt Submersible Heater ensures consistent and precise temperature control for aquariums up to 30 gallons. Built with superior European components, this heater delivers exceptional reliability and performance
  • Mirror Technology: Designed with a unique reflective finish, the aquarium heater seamlessly blends into your tank by mirroring its surroundings. Innovative feature enhances the aquariums aesthetics while maintaining an unobtrusive appearance
  • Compact & Sleek Design: The Fluval M Series heater boasts a slim profile, making it easy to position discreetly within your aquarium. Its compact size ensures it doesnt take up unnecessary space, allowing for an uncluttered tank environment
  • Versatile for All Aquariums: Ideal for both freshwater and saltwater tanks, the Fluval M 100 Watt heater provides stable and uniform heating to create a comfortable and healthy aquatic habitat for your fish and plants
  • European Quality: Engineered with high-quality materials & advanced construction techniques, aquarium heater is designed for durability & long-lasting performance. Trust Fluvals expertise in aquatic products for a safe and efficient heating solution

Description

Fluval M100 Premium Aquarium Heater is quality manufactured in Europe using superior components and construction. Sleek and compact, the submersible heater provides exceptional performance and unsurpassed reliability.

Is Discontinued By Manufacturer ‏ : ‎ No


Product Dimensions ‏ : ‎ 4.8 x 1.8 x 14.8 inches; 9.86 ounces


Item model number ‏ : ‎ A782


Date First Available ‏ : ‎ August 19, 2004


Manufacturer ‏ : ‎ Rolf C. Hagen (USA) Corp.


Best Sellers Rank: #6,883 in Pet Supplies (See Top 100 in Pet Supplies) #16 in Aquarium Heaters


#16 in Aquarium Heaters:


Customer Reviews: 4.4 4.4 out of 5 stars 5,420 ratings


Item Weight: 9.9 ounces


Manufacturer: Rolf C. Hagen (USA) Corp.


Item model number: A782


Date First Available: August 19, 2004


Item Package Dimensions L x W x H: 14.76 x 4.76 x 1.77 inches


Item Dimensions LxWxH: 4.8 x 1.8 x 14.8 inches


Item Weight: 9.86 ounces


Brand Name: Fluval


Target Audience Keyword: algae-eaters, betta-fish, bottom-feeder-fish, cichlid-fish, fish, goldfish, invertebrate-fish, mollusks, octopuses, rays, sharks, snails


Directions: Built in reflective technology mirrors the surrounding colors, making the heater blend into your aquarium environment Shock resistant Borosilicate glass; High density ceramic heat sick Slim profile tube for easy placement; Easy to install Exceptional performance and unsurpassed reliability Suitable for aquariums up to 30 gallons; 100 watts; 3 year warranty


Warranty Description: 3 years; The Fluval M series Submersible Aquarium Heater is guaranteed for defective parts and workmanship for a period of 3 year. We reserve the right to repair or replace, at our option. This guarantee excludes damage, breakage of the glass tube or injuries resulting from negligence or other misuse. This warranty does not include responsibility for animate or inanimate matter contained in the aquarium and is limited to the heater unit only. This appliance is factory sealed, tampering will void warranty.


Model Name: A782


Color: None Specific


Size: M100


Material: borosilicate glass


Age Range Description: All ages


Number of Items: 1


Style: M100


Breed Recommendation: All Breed Sizes


Included Components: Fluval M Submersible Heater


Specific Uses for Product: Indoor


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Feb 17 – Feb 18

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

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Top Amazon Reviews

    • Great product!!!
Size: M50
Review Image by Oklahoma Mom Oklahoma Mom
I love this heater. I have been using it in my betta's tank for about a year, and so far, it has worked very well! This heater is not made for being completely submerged under water. The black and grey part (the part above the little wavy marks) must be above water, along with the cord. I put this heater right next to my filter so that the filter motor can move the warmed water around the aquarium evenly. This heater is, of course, automatic. It has a thermostat somewhere in it that tells it to turn on when the water is too cool and turn off when the water gets warm enough. When the heater is warming your tank water, there will be a blue light on the side, and when it turns on and off, it will make a clicking sound and the light will turn on or off. This is a very good heater for my five-gallon tank. I have it set at about 81 degrees, and it keeps my tank at a steady 78 or 79 degrees Fahrenheit (which is the perfect temperature for betta fish). I am very impressed! ... show more
Reviewed in the United States on November 7, 2025 by Oklahoma Mom Oklahoma Mom
    • Reliable and Low-Key (in the Best Way)
Size: M150
This Fluval heater is a solid piece of equipment. I’ve had it running for almost 2 years now and it’s still performing like a champ — keeps the water at just the right temp without any fuss. The borosilicate glass design is a nice touch — it blends into the tank much better than those bulky, obvious heaters. You can still see it, but it’s not screaming for attention. The temperature dial is easy to use and overall it feels well-built and dependable. If you’re looking for a heater that just works and doesn’t make your tank look like a science experiment, this is a great pick. Its a good size, nice and slim and definitely worth every penny. ... show more
Reviewed in the United States on July 25, 2025 by Michael
    • Good reliable heater.
Size: M200
This M series 200 watt heater is a bit overkill for my 32.5 gallon tank. But it works great! I however wouldn't rely on the temperature setting gauge on the device. The best way to properly setup a heater is to set it to come on at just the right temp you want it at. Then monitor the temps over the next few hours and raise or lower the dial to match the actual temperature you want. The dials are seldom that accurate on their own. Try to attach the suction cups near the top. Don't have the holder setting on the coil area as it can melt the plastic. Also don't let the heat bulb touch anything near it. It can damage whatever it touches and can be damaged if something is leaning on it when it turns on. Place this heater away from invertebrates and snails. They can be burned or killed if the heater turns on when they are crawling around on it. These M series Fluval heaters are good heaters and I've used different wattages of them for years. But if you use them, pay attention to your tank's temps. If they stick on, they can cook your inhabitants. If they don't turn on, your tank temp could also get too cold. These heaters also are not intended to change the temp of the tank water more than 10-15 degrees total over time. They should not be used for outside use or when the room temp is way below the temp you want your tank water. They are designed to heat a few degrees only. Be sure the glass tube is not cracked or broken. Water must not contact the inside of the tube. ... show more
Reviewed in the United States on June 1, 2024 by Don Gray
    • Some flaws but overall good heater
Size: M200
Have used these heaters for years on my tanks and they work well. I like the simple design and it is easy to adjust the temp, just turn the dial on the top. It is not completely camouflaged but the mirrored surface does reflect its suroundings and I like the silver color. The temp will fluctuate a couple degreees but not a big deal and expected due to temp changes in our home. The suction cups are sturdy and stay in place on the tank sides. The title of this add it says submersible, but on the heater itself it says to not submerse below this line. However I have used these for years submersed with zero problems. Fluval is a brand I trust. The size is perfect, not too long. I recenty bought the 200 watt and the length is about 10 inches. Fits nicely on the side of the tank. Another brand I bought (starts with an E) was much longer and I had to put it in diagonally. Not sure why the size is so different but I like the shorter size. The thing I dont like about this heater is that the top is too big. If I place it vertically following the directions with the dial out of the water, the top of the heater hits the rim of the tank. I like to have the dial within easy access, but it will not fit following their directions in any of my tanks. It would fit If they designed it so that the suction cup holder held the heater at more of a distance from the tank side or if they made the top narrower. Another thing to consider is that this heater has no plastic guard on the bottom. The bottom may bump on the tank sides. Both of the suction cups are attached to the plastic holder which fits on the heater, you can't change the distance between the suction cups. So if the fish swim by quiclky they can bang the bottom of the heater on the tank side. My fish are pretty big and can hit it petty hard- they have shattered the bottom of every glass thermometer so I switched to digital. Tried sliding the holder further down but the holdef fits too loosely and the heater is top heavy, so I added another suction cup at the bottom of this heater just to be safe. For the price I think this a good heater. ... show more
Reviewed in the United States on January 21, 2015 by Jean1960
    • Fantastic Aquarium Heater
Size: M100
Great heater for any aquarium. I have had the product over a year now and it has worked without fail. Very impressed with this aquarium heater. Worked as described for a great price. Happy with this purchase.
Reviewed in the United States on June 24, 2025 by Johnny V
    • Working well, feels really well made. Looks cool!
Size: M100
The media could not be loaded. Here's how I have mine hidden and what it looks like. Don't mind the driftwood tannins, they like it. Adjustment was easy, and the mounting suction cups/bracket are great. The cord is somewhat flat too. There is a dim blue light that illuminates when it's heating, i have it positioned so I can just barely see it, at least when my curious Cichlid isn't in the way. 🙃 If you happen to have a chrome theme in your tank, this would only add to that vibe! ... show more
Reviewed in the United States on March 7, 2025 by Junie W.

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