Last Updated on September 28, 2020 by Aiden Lindow

How To Heat A Pond

Adding heat to a pond is a must during the cold months of winter. You might not think you need heaters, but I can almost guarantee you do.How To Heat A Pond

If your pond temperature drops below just 50° F, you need to add a heater to heat your pond.

Heating your pond could be the difference between your fish surviving through the winter.


How to heat a pond

There are many different ways to heat a pond, none of them are wrong, but one of them must be done.

You can use electric heaters or not use any energy at all.

Here are the different methods I use to heat my pond:


Floating de-icer

This device is designed to float in your pond and help keep your pond ice-free during the winter months. 

It’s also equipped with thermostatic control to prevent it from overheating.

De-Icers are easy to set up and will ensure no ice forms on the top of your pond. Just set them in your pond, turn them, and relax.

If ice forms on a pond, no gas will be able to get in or out meaning no oxygen can get to your fish. No added oxygen for too long means that they could die.

Having a deicer is very important to keep your fish safe.

How To Heat A Pond

Electric heater

This is a device that turns electric current into heat. Electric heaters help to generate heat during the cold months.

You can install the small heater anywhere you want in the pond, the bottom to warm the whole pond, or near the top to prevent ice from forming.  

Putting at the top will allow for the release of gases from the pond water.

Most electric heaters are meant for fish tanks so you might have to buy a few heaters to heat the whole pond. The general rule of thumb is to have one heater for every 120 gallons.

The heaters I use are the UPETTOOLS Heater. They are very reliable and they have a dial to control the heat level.

How To Heat A Pond

Solar-powered heater

This is a device that is incredibly easy to set-up. It is a great pick for many different reasons. 

You don’t have to deal with wiring, they are environmentally friendly, and you don’t have to pay electricity to run them. 

Solar-Powered Heaters work the same as a regular heater, the only difference is that it runs off of solar power. Follow the same rules as to how many you need for your pond.


Lower water level

Lowering the level of the water in a pond will help to keep the heat in the water. 

Reducing the surface area of the water means that it has less of a chance to cool off.

Many people overlook this method of keeping a pond warm, but it could end up preventing ice from forming. 

Another trick is to add warm water back into your pond once the water level is low.

If you choose to add in warm water make sure to keep in mind two things.

One, that the water is not too hot, as it will stun your fish. 

I recommend that the water be about 30° F more than the temperature of the pond. If your pond is 40° F, the water added-in should be around 70° F.

Second, make sure you dechlorinate as you fill it back up. 

If you fill it back up you will most likely be using a sink or garden hose to refill. The water that comes from both contains chlorine which will kill your fish. 

This API de-chlorinator is cheap and will last you a very long time.


Where should you place the heater?

When deciding the placement of heaters, it is not as important as you might think. The most important part is just getting the heaters in the pond. 

I place my heaters in three main locations.



Placing heaters in the filter is the easiest and simplest way to add heaters. I add a heater into my filter when the water starts to drop at the beginning of fall. 

The heater helps the fish to adapt to the colder temperatures. This heater is not meant to keep the pond warm just to help my fish get used to cooler temperatures. 


Below Waterfall

Adding in a heater below a waterfall will help to raise the temperature of the pond. If you are expecting a cold front to come in you can place the heater in a day before.

 When the cold front hits, it will take longer for the water to cool and will prevent a steep drop in water temperature.


Pond Floor

Adding heaters on the pond floor are best when temperatures are at their coldest. The heaters on the floor will heat up the whole pond all winter and will prevent water temperatures to drop into dangerous levels.

If you notice your fish becoming extremely slow-moving and lethargic it is best to add heaters on the floor to help keep temperatures up.

how to heat a pond

Heating vs. de-icing, which is better?

When it comes to Heating vs De-icing a pond there are benefits to both, but no wrong answer.


Cool climate

If you live in a mildly cool climate I recommend that you use a pond de-icer. A de-icer will make sure no ice forms and will provide a small amount of heat into the water. 

De-icers are affective if your local temperature rarely goes below 25°F during the day.

If your pond forms thin layers of ice during the winter there is no reason to add pond heaters. Pond heaters can be effective to stimulate activity during the winter.

Warm water means your fish will stay active longer into the winter.


Cold climate

If you live in a cold climate where temperatures go below an average of 25° F, I recommend using both a deicer and pond heaters. 

The de-icer might be able to prevent ice from forming but it won’t always do the trick. 

If you receive extremely cold temperatures such as continuous nights below 0°F, ice may start to form.

Having heaters as a back up will ensure no ice forms. It is better to be safe and use both heaters and de-icers.

What is too cold for fish?

Depending on your location and climate, your fish will be able to handle different temperatures.

If you live in a very cold climate and your fish are used to water temperature to dropping they will be able to handle colder temperatures because they are acclimated to it.

The general rule of thumb is to never have your water temperatures drop below 45° F. 

All common pond fish such as koi and goldfish are cold-water fish. This means they can handle cooler water temperatures. They prefer water to be around 60° F.

Another common fish people have in ponds are Mollys and Platys. These fish are tropical fish and like to have the water closer 70° F. 

Tropical fish are at a higher risk if your water temperature drops too fast or gets too cold during the winter.

how to heat a pond

Can heaters burn fish?

Pond heaters are extremely safe and rarely harm or burn any fish. The heaters I use that I linked above have a protective cover so none of my fish can accidentally bump into the heater itself.

If you are worried that your fish may bump into your heater I recommend placing the heater in the direct flow of water.

You can put it at the bottom of a waterfall, or right in front of a jet.

This will make sure it is hard for your fish to hit the heater. 

Can my fish die if it is too cold?

Most of the time, pond fish are pretty hardy creatures and can make it through winter without a problem. Although there is an off chance your fish can die during the winter. So, is there a reason behind this madness?

Well, when the temperature starts to drop, usually around 60°-50°F your fish will begin to hibernate.

When this happens they decrease their food intake, so hold off on feeding them as much.

If you feed them too much, they won’t be able to digest it all and it will sink to the bottom.

This fish food will decompose and cause ammonia which then will break down into nitrites and nitrates which is extremely deadly to your fish. 

So, during the winter there are two main causes of death.


  • Poisonous gases- Like you’ve read above, the beneficial bacteria use oxygen to gobble up all the ammonia, which later breaks down into nitrates and nitrites. With the build-up of ammonia or nitrates can cause death to your fish. Also, in winter when the water turns to ice, it will be impossible for the poisonous gases to escape.

  • Oxygen depletion- with a layer of ice on your pond, oxygen will be limited, with little to no oxygen exchange, as it usually would in the warmer months. Your entire pond ecosystem needs oxygen. The plants, fish, and beneficial bacteria.


As I’m not a big fan of my pond fish dying, I like to use an aerator in conjunction with either a pond heater or de-icer as they work very well together.

This will ensure your pond fish live through the winter.


How to keep your pond warm


Make sure your pond is deep enough, if it is too shallow, it can easily freeze over and can cause many problems during the winter. 

So, keeping your pond deep, ensures your pond is warm during the winter and cool during the summer.



During the cold winter months, try to not feed your fish as much.

Your fish hibernate during the winter, so their bodies compress their appetite to conserve energy.

So, feeding your fish more will cause the uneaten food to sink to the bottom and cause ammonia, which is lethal to your fish.

Most commonly, during the colder months, fish will live by eating small amounts of the natural growth of algae in your pond.



The winter months can be a dangerous time for pond owners, frozen ponds, ammonia build-up, and too much debris. 

Heating a pond is just one more thing to take care of but it could be the most important.

Adding heaters is simple and will ensure the safety of your fish. 

No matter if you live in Texas and only have a few days below freezing or if you live in Michigan and your whole winter is snow, heating is a must to maintain a healthy pond.