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Where to position your aquarium heater

If you are keeping tropical freshwater fish in your aquarium you will need to heat the water to suit the preferences of the fish you are keeping.

Top tips for installing your submersible heater:

  • Position the heater at an angle for even heat distribution throughout the tank.
  • Position the heater away from any air outlets or intakes to avoid alterations in temperature.
  • Attach an appropriate thermostat to ensure that your tank’s water temperature is maintained at a constant level.
  • Never turn the heater on out of the water, or unless correctly submerged.
  • To prevent any drips entering the electric sockets, create a drip loop for the heater and low voltage cable as per the diagram.
  • Ensure there is sufficient space around the heater for water circulation

Watch the short video below on how to install the Interpet Deltatherm Submersible Aquarium Heater:

Positioning your Flat Heater:

  • Fitted to the side of the aquarium using the suction cups.
  • Bury in the substrate or gravel, this is a more permanent option as you would need to disturb the gravel to access the heater. Ensure the heater is not in direct contact with the aquarium base as this could cause damage. 
  • Hidden in the filter area of many small-type aquariums with an open filter. Use suction cups to hold it in place.

How do I know if my aquarium heater is working?

There are a few steps you can take to check if your aquarium heater is working properly:

  1. Check the Power Indicator Light: Most aquarium heaters have a power indicator light that turns on when the heater is actively heating the water. Make sure the light is on when the heater is plugged in and powered on.
  2. Use a thermometer: The temperature should gradually rise to the desired level and remain stable. If the water temperature is not increasing or is significantly different from the set temperature, there may be an issue with the heater.
  3. Observe the heater: Carefully touch the heater with your hand or inspect it up-close. The heater should generate heat, especially the heating element, when it is active. Be cautious when touching the heater to avoid burns, as it can get hot during operation.
  4. Check the set temperature: Ensure that the temperature on the heater matches the desired temperature for your aquarium. Make adjustments if necessary.
  5. Monitor fish behaviour: Pay attention to the behaviour of your fish. If your fish appear lethargic, stressed, or display unusual behaviour, it may be a sign that the water temperature isn’t being maintained.

If you suspect any issues, it is recommended to consult the manufacturer’s instructions or seek advice from a professional aquarist.

How long do aquarium heaters take to heat up?

For a new tank, it may take around 24 hours for a heater to warm the water to the correct temperature.

The amount of time it takes for an aquarium heater to heat up the water depends on several factors, such as the size and material of the heater, wattage, and volume of water. If you are using a larger or more powerful heater, it will heat up the tank more quickly.

How to adjust temperature on an aquarium heater

To lower the temperature in the tank, follow these steps:

  1. Wait until the indicator light on the heater is on.
  2. Carefully turn the thermostat down until the light just turns off.
  3. Leave the heater for another half hour or more.

4. If the temperature is still too warm, repeat steps 2 and 3 until the desired temperature is reached.

Why do aquarium heaters need to be at an angle?

Aquarium heaters need to be at an angle in order to ensure even heat distribution throughout the tank. If positioned horizontally, the heater will only be able to produce a single source of warmth with limited circulation.

By positioning the heater at an angle (ideally 45 degrees), it will create a more even temperature distribution by releasing warm water from the top and cooler water from the bottom. This will ensure that the tank’s temperature is consistent.

Is it better to have 1 or 2 heaters in an aquarium?

It is generally recommended to have two heaters in an aquarium, especially if it’s large. This provides backup in case one of the heaters stops.

However, if you have a smaller tank, one heater can be sufficient. Just make sure the heater is large enough to heat the entire tank, and positioned correctly for even heat distribution.

Do aquarium heaters use a lot of electric?

The wattage of the heater depends on the size of your tank. However, most aquarium heaters range from 25 to 300 watts. A general rule of thumb is the bigger your tank, the more power it will require. Having multiple heaters may also increase the wattage.

For more information on heating your aquarium please see our Aquarium Heating FAQ’s.

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