What is the Best Water Heater for a Fish Tank with Angelfish

A water heater for a fish tank will keep your aquarium at a constant and comfortable temperature for your angelfish. Some aquarists feel that it’s better to choose a lower wattage heater so that if the contacts malfunction and permanently close, the water won’t become overheated. Others feel that choosing a heater on the higher end of the wattage output, it won’t overwork the heater and keep water warm in instances of abnormally cool weather. Both have valid reasons for their views.

How to Choose the Best Aquarium Heater

Choosing the correct heater for a tank depends on two things. Aquarium size and the temperature difference between the coldest ambient room temperature, and the tank temperature. Angelfish live in a temperature range of 75 – 82 degrees and prefer closer to the 80 degree range. The smaller the temperature variation, the lower wattage heater needed. The following list gives the temperature differential between ambient and tank temperatures for the proper heater wattage for the aquarium size. Most aquarium heater manufacturers make the same model in a variety of wattages to accommodate different tank sizes and conditions.

Fish Tank SizeDesired Temperature IncreaseWatts You NeedHeater Recommendation
5 gallon (25 liter)

9 degrees F (5 degrees C)

18 degrees F (10 degrees C)

27 degrees F (15 degrees C)

25

50

75

Jager Fish Tank Heater
10 gallon (50 liter)

9 degrees F (5 degrees C)

18 degrees F (10 degrees C)

27 degrees F (15 degrees C)

50

75

75

Jager Fish Tank Heater
20 gallon (75 liter)

9 degrees F (5 degrees C)

18 degrees F (10 degrees C)

27 degrees F (15 degrees C)

50

75

150

Aqueon Pro Heater
25 gallon (100 liter)

9 degrees F (5 degrees C)

18 degrees F (10 degrees C)

27 degrees F (15 degrees C)

75

100

200

Aqueon Pro Heater
40 gallon (150 liter)

9 degrees F (5 degrees C)

18 degrees F (10 degrees C)

27 degrees F (15 degrees C)

100

150

300

ViaAqua Aquarium Heater
50 gallon (200 liter)

9 degrees F (5 degrees C)

18 degrees F (10 degrees C)

27 degrees F (15 degrees C)

150

200

Two 200-watt heaters

Pro Heater
65 gallon (250 liter)

9 degrees F (5 degrees C)

18 degrees F (10 degrees C)

27 degrees F (15 degrees C)

200

250

Two 250-watt heaters

Pro Heater
75 gallon (300 liter)

9 degrees F (5 degrees C)

18 degrees F (10 degrees C)

27 degrees F (15 degrees C)

250

300

Two 300-watt heaters

Aquatop 300-watt Aquarium Heater


Aquarium Heater Features to Look For

Aquarium heaters offer a variety of features.

  • An adjustable aquarium heater allows raising or lowering the temperature to adjust the tank temperature with and adjustable dial.
  • Others have shatterproof glass to protect against breakage. Shatterproof glass is an excellent safety feature on this model.
  • Most offer a light to indicate if the heater is or off.
  • Some are fully submersible and will shut off if the water level becomes too low.
  • Aquarium heaters with a visible temperature setting is a nice feature. However, these aren’t always accurate and it’s prudent to check water temperature against a thermometer and adjust the heater accordingly. When checking temperature with a thermometer, keep it as far away from the heater as possible.
  • A dial on the top of the heater is the normal way to adjust the temperature. The visual display has a range between temperatures, so it’s advisable to check with a thermometer to get a more accurate reading.
  • High end aquarium heaters may use a digital display to show water temperature. The Fluval E samples the water temperature rather than air in the tube to obtain a more accurate reading of the actual water temperature.

All aquarium heaters do the same thing, some more precisely and accurately than others.

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