Heaters · Adjustable submersible
Fluval M100
Manufacturer-rated for aquariums up to 30 US gal.
Slim 100 W adjustable submersible heater with a 66–86°F maker-published control range.
Consider: A cold room or open tank changes the heating load. Use the exact-model sizing chart with your coolest room temperature before choosing from the gallon rating alone.
US version, item A782. Check what’s in the box before you buy.
Tank size Fluval rates it for
Up to 30 US gal
Choose your tank to see where it falls.
Check it against your tank →Specifications that affect fit
- Manufacturer capacity
- Up to 30 US gal
- Power
- 100 W
- Supply voltage
- 120 V / 60 Hz
- Dimensions
- 11 × 1 × 1 in (L × W × H)
To see what it costs to run, enter the watts on its label and your daily hours in the electricity cost calculator.
Before choosing this model
- Confirm item A782 rather than a 150 W M-series variant.
- Verify water temperature with a separate thermometer.
Our buying guides size it for these tanks:
5 gallon10 gallon20 gallon29 gallonBetta tank
A heater rated for your tank can still fall short in a cold room: see how to size one.
Check it against your tank → Something not working? See the troubleshooting guide.
Included items & upkeep
- heater
- mounting bracket
- suction cups
Plan for the routine work
- Unplug and allow the heater to cool before removal.
- Follow the model manual's water-level, placement, and inspection instructions.
To budget for replacement media and supplies, use the first-year cost calculator. For how often and how to clean it, follow the maker’s manual.