This Site Uses Cookies
This site uses cookies to improve your experience. By continuing to use & browse this site, you agree to the Privacy Policy and accept the use of cookies.
Reef Stable is a small business focussed on educating and providing the best coral for beginner reef keepers

Disclaimer: This page contains advertisements and/or affiliate links. We receive compensation from clicks and/or purchases made through these links. Though we may not have tested the specific product(s) mentioned, we do our best to recommend products that are beneficial to our visitors.

How To Heat an Aquarium with Natural Gas

Share this article:
Pin it!

Last updated on November 17th, 2023


Wall to Wall Reef Tanks

Heating an Aquarium with Natural Gas

If you are reading this article about heating your aquarium with natural gas, then you have likely felt the pain of the cost of electricity with your aquarium. Most of this cost is likely from heating for reef tank. Though this is intended for reef tanks, particularly large reef tanks, this can also apply to heating your freshwater aquarium with natural gas.

In most areas, natural gas is cheaper per BTU than electricity. That being said, it's possible that isn't true for you. I heard about some people in Texas getting electricity for less than $0.07 per KWh. If this is you, you likely don't use enough energy to make up for the cost of the setup. This is something you will have to calculate for yourself.

Shop Coral at Reef Stable


Before considering or doing anything in this article, I must note that this is AT YOUR OWN RISK, and Reef Stable is not responsible for what/how you do this! You may consider contacting a contractor, your home insurance company, and/or city for any permits and legal requirements before modifying components of your home and/or gas appliances for the benefit of your aquarium.

Home Modifications to Consider

This method of heating your aquarium with natural gas DOES NOT include modifying your home's gas line. It DOES include modifying the plumbing to your natural gas water heater. Obviously, there are things to keep in mind, such as never letting the water from the hot water heater mix with aquarium water. Aquariums contain bacteria and other contaminates that can have negative health affects. Always put you and your family's health above that of your aquarium!

Benefits of Heating an Aquarium with Natural Gas

The only benefit of heating an aquarium with natural gas is to reduce the cost of electricity while heating your aquarium. It doesn't make sense to heat small aquariums with natural gas because the cost to set up this system is far more than you will save. One of my aquarium costs about $52 per month in heating. This process can reduce that to roughly $16 per month in my area. So even at the high startup price, it pays for itself within only a couple years.

How Much Can You Save Heating Your Aquarium with Natural Gas?

This is the nerdy section, and is mostly assumptions that I have no plans to prove. But this will give you an idea on how much money you may be able to save heating your aquarium with natural gas. This may help you decide if it is worth it for you.


Firstly, I am assuming that electric aquarium heaters are 100% efficient. They aren't, but they are fairly close. So I am using that as a number to beat. Secondly, I am assuming that the gas heat is only 75% efficient. I have no idea how close this would be as there is heat loss from the water flowing through tubing and a number of other locations. So I feel this is a safe number, but I may be way off.

How Much Does Electric Heating Cost?

My tank uses about 360 kWh of electricity for heating. You can figure this out by monitoring how many hours your heaters are on and multiply them by the wattage/1000 per month.

Example: 360 hours/mo * (1000 W Heaters / 1000 W/kW) = 360 KWh

Then multiply that by the cost per kWh:

Example: 360 KWh * $0.14488/kWh = $52.16/mo

How Much Gas Does it Need

Each kWh is equal to 3412 BTU of heat. This means that we need to find out how many "therms" this is equal to. 1 Therm is 99976.1 BTU, meaning that the kWh to Therms looks like this:

Example: (360 kWh * 3412 BTU/kWh) / 99976.1 BTU/Therm = 12.29 Therms

The cost of this is then based on your energy company. My cost is $0.972675/Therm. This means the cost would be $11.95/mo. I am claiming about 75% efficient so that would be $11.95/0.75, meaning it is more like $15.67/mo. This would be a savings of $36.49/mo or 70%! So with my rates, this saves $70 for every $100 used in heating!

How to Heat Your Aquarium with Natural Gas

Before Modifying Plumbing

Before making modifications to your hot water heater, you should shut off the cold water entering the hot water tank and the hot water line. Additionally, you need to drain the tank to prevent burns from the hot water.

Plumbing for the Hot Water Tank

When plumbing your hot water heater, remember this is residential plumbing, not aquarium plumbing. You need to think about things such as copper vs galvanized plumbing, threaded vs sweat, and other decisions of that nature. You may want to reach out to a local plumber to have this done right. If you don't know what you're doing, DO NOT attempt to modify your home water system.

What You Will Need

  • 2x Tee - For your hot and cold water lines
  • 2x+ Shutoff Valve for Hot Water into Heat Exchange System and one going back to the cold water. As well as any others you may want.
  • 4x+ Unions - Use these on both sides of the heat exchanger and both sides of the pump, and anywhere else that may need to be removed.
  • Misc. plumbing depending on how/where you plan to install this system.
  • Circulation Pump, such as the Grundfos
  • All Titanium Heat Exchanger

Plumbing Installation

You will need to install a Tee joint after the existing cold water shutoff into your hot water tank. The Tee will then branch off to a dedicated shutoff valve for the aquarium's titanium heat exchanger. You will then install plumbing to a circulation pump, such as the Grundfos. Make sure to use a pump rated for the temperature and can work with the type of plumbing in your home. The pump will then be plumbed from the the hot water line to the Heat Exchanger.

Finally, the outlet of the heat exchanger is plumbed back to the hot water heater. This can be done using either the cold water inlet, or the drain on the bottom of the tank. Both of these options will allow the water back into the hot water tank for reheating.

How To Heat an Aquarium with Natural Gas

Tank Plumbing

The aquarium will then need a return pump to push water through either PVC or Vinyl to the heat exchanger and back to the tank. Both this pump and the hot water circulation pump should be plugged into a temperature controller to turn the system on and off as needed.

Shop Coral at Reef Stable


Overall, heating your aquarium with natural gas may not be the bast route, especially since it may cost around $1000 to set up. But if you are saving 70% or more on heating, you may be able to make that money back in a year or less! This all depends on your location, however, in cost states with high electric cost, natural gas heat is a great way to save the budget!

Recommended Reading:

Share this article:
Pin it!

About the Author

Reef Stable Founder John Krenzer

John is a Software Engineer with a passion for saltwater aquariums, as well as the founder and president of Reef Stable. He started in the aquarium hobby as a child with a 20 gallon freshwater aquarium. His interest in aquarium life grew and in 2008, John set up his first saltwater aquarium.

Today, John maintains an over 300 gallon reef tank system, consisting of a 120g reef and a 210g reef. These large tanks are contained within the same system, sharing a sump as a means to reduce total maintenance and increase total water volume.

John writes articles for the blog as a means to learn about more reef aquarium topics. These articles act as a reference for the readers as well as himself. John updates these articles frequently to provide additional information or make corrections as new information becomes available.

If you would like to request an article, tank tour article, or to collaborate, let me know via the Contact Me Page!

About Reef Stable

Reef Stable was initially founded in 2019 as a reef tank parameter log to fill a need. Reef Stable quickly grew, becoming a location to solve all of your reef tank problems as well as a place to learn.

Reef Stable now provides a Reef Blog, Reef Aquarium Guides, Coral Care Guides, Identification and Solutions for Pests and Algae, and Reef Dosing Calculators, in addition to the original Reef Parameter Log.

Reef Stable continues to grow, striving to provide a single location for all your reef tank needs!

Swim With Us!

Follow Reef Stable on your Favorite Social Media Platforms!

Reef Stable Facebook PageReef Stable Instagram PageReef Stable Pinterest PageReef Stable Youtube Page

+1 (414) 810-7878

© 2019-2021 Reef Stable, LLC. All rights reserved.