Cobalt Aquatics

Neo-Therm Submersible Heater

Grouped product items
No options of this product are available.

Cobalt Neo-Therm heaters are very unique.  They have a super thin profile that allows them to fit into tight spaces like on AIO compartments, or sump baffles. With its easy to set and easy to read control system, setting a heater has never been this easy.

  • Easy to set "One Touch" control
  • Advanced electronic thermostat - Accurate to ±0.5ºF
  • LED Display - shows the Set Temp and Tank Temp simultaneously
  • Set temperature range from 66ºF up to 96ºF
  • Safety features


Safety Features - integrated thermal protection circuitry shuts the heater down before it can overheat. The outer casing is shatterproof making the NEO-therms virtually indestructible. Use for freshwater and saltwater aquariums and terrariums.


Correct heater position- Vertical with heating element down, bezel, cord, and button up.

  • Minimum water level - Top of the bezel.
  • For 25, 50, 75 Watt - 5.5" from bottom of the heater
  • For 100 Watt - 8.75" from bottom of the heater
  • Maximum depth of 31.5" deep at the bezel


Quick Compare - Cobalt Neo-Therm Submersible Aquarium Heaters

Model No.Maximum Aquarium SizeDimensions
25W 6 Gallons 6 1/2" L x 2 1/8" W x 4/5" Thick at Bezel
50W 12 Gallons 6 1/2" L x 2 1/8" W x 4/5" Thick at Bezel
75W 20 Gallons 6 1/2" L x 2 1/8" W x 4/5" Thick at Bezel
100W 29 Gallons 9 3/4" x 2 1/8" x 4/5" Thick at Bezel
150W 40 Gallons 10 7/8" x 2 1/8" x 4/5" Thick at Bezel
300W 75 Gallons 10 7/8" x 2 1/8" x 4/5" Thick at Bezel

Note: 300W model consists of two connected heating elements that measure 10 7/8" x 2 1/8" x 4/5" each.


Owners Manual

Write Your Own Review
You're reviewing:Neo-Therm Submersible Heater
Your Rating
Only registered users can write reviews. Please or

Product Questions

Can these be mounted horizontally? The manual from cobalt has a big X in a photo over them being sideways, and only shows them OK upright. Your overview here says they can be submerged at any angle though... don't know how anyone would fit anything 100w and up completely underwater in a sump straight up and down.
Question by: Ken on Dec 27, 2017, 1:30 PM
Thanks for reaching out to BRS!

Regrettably, the quick overview is incorrect. This heater should not be mounted in any position other than vertically, with the cord and buttons at the top. We will get that updated ASAP. Have a great day.
Answer by: Josh Cuta on Jan 2, 2018, 11:10 AM
Just bought a Nuvo 20 from you guys. The chart says 75W for 20 gallons, so should I just follow that or would 100W be more reliable?
Question by: Matt on Dec 3, 2017, 4:28 PM
Hi There,
Heaters are one item that I would not recommend going higher than what you need. If the thermostat were to fail in the on state and you had a larger one in the tank it would cause problems faster. I would stick with the 75 watt recommendation.
If you have any other questions please let us know!
Answer by: William Glenn on Dec 4, 2017, 4:38 PM
I have a 46 gallon bowfront with a 20 gallon sump, given water displacement from live rock and filter media such as protein skimmer and reactors and live sand, would a 150watt be sufficient enough to heat the tank?
Question by: Jeffrey Crupper on Jun 9, 2017, 3:00 AM
For the majority of setups and environments, the 150 watt heater should be just right!

Have a great day!
Answer by: Zack on Jun 13, 2017, 11:02 PM
How many amps does the 200 watt heater pull?
Question by: Scott on Jun 4, 2016, 1:22 PM
Great question!
We expect around 1.6 amps. Feel free to let us know if you have any further questions!
Answer by: Connor on Jun 8, 2016, 5:46 PM
I have a 2 1/2 gallon tank for my betta.
Is the 25Watt Neo-Therm ok for me to use in my tank?
I would like to set it about 78 and hold it there.
My last heater rose the water to almost 88. Not good.
Question by: Judy on Jun 1, 2016, 3:08 PM
Great question!
Typically 2.5-5 watts per gallon are recommended. While the 25 watt could work if left on the lowest setting and certainly can work well with safety built in it has the potential to over heat if left on too warm of a setting.
Answer by: Connor on Jun 2, 2016, 11:31 AM
I have a 94 gallons tank.
What kind of cobalt heater do I need, how many watts
Question by: Osvaldo Leon on Feb 7, 2016, 4:20 PM
Great question!
You will want 2 of the 200 watt heaters for good coverage of your tank! Feel free to let us know if you have any further questions!
Answer by: Connor on Feb 10, 2016, 6:13 PM
Once the temperature is set, if my Apex unit cuts power to the outlet (temp gets out of range) does the heater remember the last set temp or does it reset to a default? If it is a default, what is it?
Question by: Nick on Apr 11, 2014, 6:27 AM
Hey Nick,
The heater should remember the tem, but that said with a setup like this what you would want to do is set your heater for your desired temp (say 78 degrees) and then set your Apex as an emergency cutoff to cut the power if the temp gets too hot and it appears the heater has failed (say 79.5 degrees). That way the heater is in primary control and you will avoid constantly cutting power to and from it (which may be hard on the heater).
Answer by: Bulk Reef Supply on Apr 11, 2014, 6:27 AM
Is there a calculator that helps you determine what sized heater I need for each of my tanks?
Question by: Debbie on Mar 31, 2014, 3:04 AM
Hey Debbie,
There isn't a calculator as each heater is a bit different, but all of the manufacturers do have recomended size aquariums for their heaters. If you look at the full details of this page there is a quick comparison chart to help you match the heater size to how big your aquarium is.
Answer by: Bulk Reef Supply on Mar 31, 2014, 3:04 AM
I have a 10 gallon tank right now. I also have plans in the future to expand my tank size to around 20-30 gallons in the future. If I buy the 100 watt heater now and put it in my ten gallon tank with the idea of using this same heater in the future would it be complete overkill? Would putting in this high watt output heater be detrimental on the 10 gallon tank?
Question by: Sloan on Feb 8, 2014, 9:04 PM
Hi Sloan,
Thats not a problem at all. If the heater is larger it just won't run for as long, nothing to worry about!
Answer by: Bulk Reef Supply on Feb 8, 2014, 9:04 PM
Will this heater shut off if it is not all of the way in the water? When doing water changes on my solana, the area that the heater will go in will be out of the water for a few minuets
Question by: James on Feb 4, 2014, 11:09 AM
Hi James,
It won't shut itself off (I don't know of any heater that would). You will want to unplug it before its removed from water (or if you have an aquarium controller you setup something like a feed mode to shut down your pumps, heaters, etc at the press of a button for when you do a water change).
Answer by: Bulk Reef Supply on Feb 4, 2014, 11:09 AM
I'm just waiting on the Apex gold to come out. I want to put an 85 gal coral frag/semi show tank together. With the Apex , can I run two cobalts in tandem or do i need a bigger heater than the biggest Cobalt Neo therm? I think its only good to 55 gallons . Plus I have the sump volume aswell do factor in.
Question by: Tom Kinakin on Jan 20, 2014, 3:04 AM
Hey Tom,
I think they should be here this week :-) The different outlets have different amperage allotments but in general unless you are using two very large heaters your not going to run into any issues :-) Just for example, the 8amp outlet would be able to power about a total of 950watts. Should be way more then plenty for a 55g tank!
Answer by: Bulk Reef Supply on Jan 20, 2014, 3:04 AM
I am in the process of setting up a 40 gallon hex reef tank, and would like to get a recommendation for a heater. I am not wanting to get the latest and greatest model. Just something reliable and not glass.

Question by: Nick James on Jan 16, 2014, 9:50 AM
Hey Nick,
Most of us around here use the Neo-therm but the second most popular has to be the finnex HMO series heaters. Assuming you don't have an aquarium controller yet I would get something that has a digital thermostat as they are a lot less likely to fail (in particular in the ON position).
Answer by: Bulk Reef Supply on Jan 16, 2014, 9:50 AM