Search  for anything...
Fluval

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

  • Based on 5,420 reviews
Condition: New
Checking for the best price...
$32.99 Why this price?

Buy Now, Pay Later

As low as $8 / mo
  • – 4-month term
  • – No impact on credit to apply
  • – Instant approval decision
  • – Secure and straightforward checkout

Ready to go? Add this product to your cart and select a plan during checkout.

Payment plans are offered through our trusted finance partners Klarna, Affirm, Afterpay, Apple Pay, and PayTomorrow. No-credit-needed leasing options through Acima may also be available at checkout.

Learn more about financing & leasing here.

Selected Option

Free shipping on this product

FREE 30-day refund/replacement

To qualify for a full refund, items must be returned in their original, unused condition. If an item is returned in a used, damaged, or materially different state, you may be granted a partial refund.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

Availability: In Stock.
Fulfilled by Amazon
Arrives Friday, Apr 24
Order within 59 minutes
Available payment plans shown during checkout
Protection Plan Protect Your Purchase
Checking for protection plans...

Recently Viewed

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.

Material: borosilicate glass


Brand: Fluval


Color: None Specific


Wattage: 100 watts


Item Weight: 9.86 ounces


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: #7,100 in Pet Supplies (See Top 100 in Pet Supplies) #13 in Aquarium Heaters


#13 in Aquarium Heaters:


Customer Reviews: 4.4 4.4 out of 5 stars (5,548)


Brand Name: Fluval


UPC: 015561107822


Global Trade Identification Number: 22


Manufacturer: Rolf C. Hagen (USA) Corp.


Item Type Name: Submersible Heater


Included Components: Fluval M Submersible Heater


Unit Count: 1 Count


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.


Material Type: borosilicate glass


Color: None Specific


Wattage: 100 watts


Item Weight: 9.86 ounces


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Friday, Apr 24

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.

  • Klarna Financing
  • Affirm Pay in 4
  • Affirm Financing
  • Afterpay Financing
  • PayTomorrow Financing
  • Financing through Apple Pay
Leasing options through Acima may also be available during checkout.

Learn more about financing & leasing here.

Similar Products

Top Amazon Reviews

    • Great product!!!
Size: M50
Review Image by 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
    • Good heater from a reputable company
Size: M200
I really like how oversized these are it seems efficient - getting these dialed in on the temp requires another thermometer imo that is calibrated And I think the safest bet is an ink bird or equivalent as a backup thermometer Incase of it breaking and ending up stuck on - I don’t do this (maybe yet?) but for an exspensive or huge tank I would consider it ... show more
Reviewed in the United States on March 18, 2026 by Beanieoh
    • 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
    • The only heater that reliably works for my 10‑gallon tank
Size: M150
After trying several different aquarium heaters, this Fluval M 150‑watt model is the only one that has consistently kept my 10‑gallon tank at the correct temperature. It heats evenly, stays stable, and doesn’t fluctuate the way other brands did. For a small tank that needs dependable temperature control, this has been the most reliable option I’ve used. For ambient air context, it's winter and the house dips to 60 degrees at night. I have a cover on the tank which is essential. ... show more
Reviewed in the United States on January 18, 2026 by Tom & Chris
    • 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
    • Heater Couldn
Size: M100
Review Image by DL
Review Image by DL
I've only had this heater for a month and already need to buy a new one. It was working fine the first week or so and kept the water a consistent temperature but I began to notice the temperature creeping down this past week. When I took the heater out to check it, I saw the heater was actually melting the suction cup holder!! It smelt like burning plastic. This could've killed my turtle and/or eventually started a fire!!! Very upsetting considering all of the seemingly positive reviews. Can't even return and get my money back because the return window ended two days ago. ... show more
Reviewed in the United States on February 10, 2026 by DL
    • Great heater
Size: M100
Goes a great job at keeping the tank up to temp
Reviewed in the United States on February 27, 2026 by Andrew

Can't find a product?

Find it on Amazon first, then paste the link below.
Checking for best price...