Eheim Thermocontrol Aquarium Water Temperature Controller, 125-watt

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$49.99 Chewy Price
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Pay in 4 interest-free payments of $12.50. .

About This Item

Details

  • Suitable for both freshwater and saltwater environments.
  • Designed so that heat is kept constant.
  • Equipped with a temperature indicator that’s red when heating up and green when the desired temperature is reached.
  • Crafted for safety and reliability.
  • Made in Germany.

Instructions

Questions & Answers

2 Customer Questions

is this compatible with a 20 gallon tank? I recently upgraded from a 10 gallon and the heater I currently have can't keep my 20 gallon heated enough

Answer by Chewy • Sep 08, 2021
The 125-watt temperature controller is suitable for aquarium of around 150 litter or approximately 40 gallons and up to 200 liters or approximately 53 gallons.

Hi, description and key benefit notes indicate fresh and salt water...but item details at bottom of page indicate "freswater". I have a saltwater reef tank and want to be certain it's designed for saltwater . thanks

Answer by Chewy • Sep 04, 2021
The heater is suitable for fresh and marine water (saltwater).
Reviews
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3.7
Rated 3.7 out of 5 stars
13 Ratings
Terms & Conditions

6 Customer Reviews

Rated 4 out of 5 stars
By Destiny on Aug 30, 2025

Progress after 11 Days

My betta loves it and hides around it. I have it set to 82, but my Fluval digital thermometer says the tank temperature remains between 79 and 80 degrees. My only

My betta loves it and hides around it. I have it set to 82, but my Fluval digital thermometer says the tank temperature remains between 79 and 80 degrees. My only complaint is how bulky the heater is in my Biorb Classic 30L tank. Only one suction cup can attach to the tank, thus I keep it lying down in the tank. Other than that, I wholeheartedly recommend this for your fish baby.

Rated 5 out of 5 stars
By Sarah on Apr 15, 2025

So far so good

Needed it for shallow water (frog tank) and therefore turned it sideways (counter to instructions). Seems to be working great so far! (About two weeks)

Needed it for shallow water (frog tank) and therefore turned it sideways (counter to instructions). Seems to be working great so far! (About two weeks)

Rated 1 out of 5 stars
By Linda on Oct 21, 2022

Eheim, Scham dich! (Shame on you) 5 days failed!

Received the 125 watt on 10/15. Installed in my tank next day, tonight, 10/20, it is not producing any heat even though the red light is on. It worked perfectly

Received the 125 watt on 10/15. Installed in my tank next day, tonight, 10/20, it is not producing any heat even though the red light is on. It worked perfectly until today. My go to brand for years, made in Germany, is now like the cheap knock offs. Sooooo disappointed Eheim!!

Rated 1 out of 5 stars
By megs on Aug 31, 2022

So So Bad!!!

This filter sucks. It can’t maintain temp at all. I now have it up to what should be 87° in my 20 gallon tank and it is only holding at about 80° all the time. I

This filter sucks. It can’t maintain temp at all. I now have it up to what should be 87° in my 20 gallon tank and it is only holding at about 80° all the time. I like it around 82° because our winters are cold and we run the AC during the summer. The red light is always on because the temp is wrong. Very annoying

Rated 1 out of 5 stars
By Fountain on Jul 23, 2022

Aquarium Heater

This heater is supposed to work to heat a tank larger than the 35gal tank I own and it won’t heat it over 70 degrees.

This heater is supposed to work to heat a tank larger than the 35gal tank I own and it won’t heat it over 70 degrees.

Rated 5 out of 5 stars
By Heather on Sep 30, 2021

Works great!

I put this heater in a 20 gallon divided tank and was unsure if it would be able to maintain temp on both sides. It has done very well and I see very little fluctuation

I put this heater in a 20 gallon divided tank and was unsure if it would be able to maintain temp on both sides. It has done very well and I see very little fluctuation. I'm very pleased with it.