What To Do When A Fish Tank Heater Gets Cracked?

If a fish tank gets cracked, the fish inside can get injured by the glasses. It also creates a fire hazard if the glass tube explodes.

You have to quickly repair or replace the heater as soon as possible. There are also a couple of safety measures that you should ensure. Preventing the heater from breaking should be your main concern.

How do the heaters become damaged? How can you prevent this situation in the future? Read on to learn all about the fish tank heater and how to safely operate them inside your fish tank.

Why Does the Fish Tank Heater Get Cracked?

Heaters come in a variety of shapes and sizes. The glass heaters, on the other hand, are breakable. You can never be sure, even if the maker claims it is indestructible.

Small to medium-sized fish won’t be able to damage the heater from touch if they’re in your fish tank. If the heater is in the middle or on the edge, it is more likely to break. So, position the heater in a corner of the fish tank.

Large fish, on the other hand, can harm the heater if they come into touch with it. The heater may crack if it is bumped too hard. Heaters are a hazard zone in any tank with huge pebbles.

All of the fish may perish if the heater breaks because of pebbles or shocks.

How to Prevent the Fish Tank Heater from Cracking?

You definitely know the term, “prevention is better than cure”. So, let us take a look at a few steps that you should follow to prevent the heater from cracking.

  1. Whenever you need to adjust the heater’s temperature, make sure it’s unplugged first.
  2. Turn the heater off before altering the heater’s location or switching it on. While moving it, it has the potential to crack at any time.
  3. Be cautious when replacing the heater’s thermostat. While adjusting the thermostat, the majority of heaters fracture.
  4. Purchase a heater that is greater than the tank’s recommended size. This reduces pressure on a heater.
  5. During water changes, disconnect your heater as well. Check that your heater isn’t touching anything in the tank.
  6. Spend the cash on a good quality heater; quality is determined by the price. Cheap heaters should be avoided since they are prone to breaking.

If you manage to follow these measures, the possibility of cracking the heater accidentally will lessen.

How to Repair a Cracked Fish Tank Heater?

If the heater’s glass becomes damaged, you can do a temporary repair in your house. First and foremost, you must determine whether or not the broken pieces can be bonded together.

Then, at the bottom of the heater, disconnect the plug cover. Then remove the thermostat from the glass.

After that, double-check that all of the connections are in working order. It’s also possible that the thermostat needs to be replaced.

The thermostat should then be placed inside. Then put the broken component in place and align it. To fix the damaged heater glass, use a strong adhesive.

Be careful to apply the glue slowly while doing so. Also, spin the tube and spread it to all of the cracks to prevent water from getting inside.

How to Use the Heater Protectors to Prevent Cracks?

Heater protectors are a good idea if you have a weak heater. When you have large, aggressive fish, a heater protector is recommended. Using heater protection not only protects your heater, but it also protects your fish.

Heater protectors are available in your nearest fish or aquarium shop. They’re also available on the internet. You can get this one from Amazon.

You may even make your own from scratch. A heater protector may be made out of plastic tubing. Use a size that allows you to easily insert the heating tubing.

Provide for circulation of water around it as well. Make sure that the pipe has enough holes drilled or cut to account for the effect of water circulation.

Both ends of the tube should be open. To keep the heater in position within the tube, connect the suction cups to the heater.

How to Place the Heater Inside to Avoid Cracks?

Make a hole in the hood of your tank if you have an immersible heater. Then, it should hold the heater in place securely.

You may also use vacuum pads to adhere them to the tank wall. You should fasten them to the lowest half of the wall. You can also place them on the fish tank’s bottom.

If you pick a submersible heater, you can submerge the entire unit in water. These heaters may be prone to damage from the inside.

But, if you own a hanging heater, only the heating portion should be submerged in water.

If you are changing the temperature of the thermostat, be sure to place the heater vertically. Also, ensure that it is placed near the filter or the pump.

Can a Cracked Fish Tank Heater Shatter?

The glass tube might burst if the fish tank heater overheats. A fire can ignite if the glass tube explodes and there is a combustible object nearby.

Remember to get a heater with heatproof wiring. This will keep it from overheating for an extended period.

However, if you attempt to temporarily fix it, there’s a good possibility it’ll break again shortly. As a result, you should acquire a new one as soon as possible.

Within your fish tank, you’ll find a variety of electrical components. So, install a multi-way socket to prevent electrical malfunctions.

What Type of Heater Should You Choose?

There are distinctions among the many types of heaters. Fish tank heaters are divided into four categories.

The most well-known heaters are submersible and immersible heaters. You can also utilize the substrate heaters or the in-line heaters.

Here are a few suggested heaters that are less prone to cracking:

  1. Tetra HT Submersible Aquarium Heater
    – Indicator lights with built-in electronic thermostat.
    – Best for 2 to 10 gallons with glass or hoods.
    – You can install them vertically or horizontally and submerge them in the water.
  2. Aqueon Aquatic Flat Heater 7.5W
    – Unbreakable design with easy installation.
    – Can warm the fish tank up to 15 degrees Celsius above room temperature.
    – Can also be fully submerged in the water.
  3. Hydor In-Line External Heater – Original ETH
    – Built with high accuracy electronic temperature controller.
    – Comes with 3 options: 200 Watt 1/2″, 200 Watt 5/8”, and 300 Watt 5/8”.
    – It’s made to go on return lines from canister filters or sumps.
  4. Finnex HMH Digital Titanium Aquarium Heater, HMH-300S
    – Heating tube made with titanium for better temperature control.
    – Protected with a heater guard.
    – Has internal sensor to prevent over-heating or low temperature.


The heater is mostly protected by glass. These are prone to breaking. If you don’t want your fish tank’s heater to be cracked, be sure to follow my instructions.

You should clean the tank regularly, install a heater protector, and install a multi-way socket. Also, follow the instructions to repair or place the heater properly inside the fish tank.

Proper maintenance should keep you and your fish safe from any kind of heater-related anomalies. So, keep your eyes sharp.

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Arif H Fahim

Welcome to PetFishTank! My name is Arif. I make an effort to publish educational articles using my many years of expertise as a fish owner.

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