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Aquarium Thermometer Buying Tips

Pro and Con Comparisons on Different Styles of Thermometers


There are many different kinds of aquarium thermometers to choose from, and although they do serve the same purpose, provide a temperature reading of an aquarium's water at all times, is there one type of thermometer that is better than another?

Aside from the desired Fahrenheit, Celsius, or combo °F and °C temp readings a unit provides, simply review the pros and cons on each style of aquarium thermometer listed here before you buy one, because there are other differences between them.

Stick-On LCD Digital Thermometers

Penn-Plax Therma-Temp Stick On Digital Thermometer
  • Pros: Inexpensive; easy peel-and-stick tank exterior application; available in movable versions; permanent location allows for quick at-a-glance reading; come in various sizes, shapes and temperature ranges.
  • Cons: May be hard to read, especially in a low lite room; the laminated thermometer materials may separate over time.
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Magnetic Thermometers

This aquarium thermometer simply uses a magnet to keep it in place inside the tank.
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  • Pros: A unique and innovative design, the thermometer goes on the inside of the tank and the magnet goes on the outside to hold it firmly in place; no suction cups needed; durable non-corrosive plastic housing; offers a green safe zone which indicates the optimal temperature range; large easy-to-read numbers; ranges from 30° to 104° F and C.
  • Cons: White plastic housing makes it visible.
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Floating Aquarium Thermometers

  • Pros: Inexpensive; compact size; colored acceptable temp zone for quick at-a-glance reading; available with suction cup included to stick the thermometer in a permanent location inside the aquarium, which provides quick at-a-glance reading.

  • Cons: May be difficult to read due to small print numbers; suction cup needs replacing when it wears out, otherwise the thermometer converts to a free-floating unit; non-suction cup version can be hard to locate because it free-floats on the surface of the water; can bob around and clink up against the walls of a glass aquarium; usually made of glass, which can break.
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Stainless Steel Thermometers

  • Pros: Inexpensive; simply hangs in the water mounted on the rim of the aquarium; convenient permanent location and usual large print numbers provide easy at-a-glance reading; made of corrosion resistant materials.
  • Cons: Large size and silver color makes these rather visible in an aquarium; sinks when dropped into the water.
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Standing Thermometers

  • Pros: Inexpensive; weighted to stay on the bottom of the aquarium, as opposed to free-floating on the water's surface; compact size; colored acceptable temp zone for quick at-a-glance reading.
  • Cons: Some units may be difficult to find in an aquarium, because although weighted they can move around, especially when used in tanks with water movement devices like wavemakers and powerheads; usually made of glass, which can break; might move around and bump up against walls of a glass aquarium and make a clinking noise; often have small hard to see print numbers.
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Basic Remote Sensor Digital Thermometers

ESU Coralife Digital Thermometer Image
  • Pros: Rather inexpensive; compact sizes; convenient same location and easy to see readings; a sensor cord is placed inside the aquarium, with the LCD display unit being mounted on the outside of the tank with suction cups, or may be hidden in an aquarium cabinet when the sensor cord is long enough.
  • Cons: No automatic temp alert feature; attached sensor cord can limit placement in aquarium, and black cord is visible; battery powered, therefore the battery requires replacing when needed.
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Submersible LCD Digital Thermometers

Dignital LCD read out submersible aquarium thermometer
  • Pros: Inexpensive; compact size; fully submersible wireless sensor units with no attached probes, therefore no unsightly cords are visible; suction cup mounted inside the aquarium; easy to see LCD readout; battery operated.
  • Cons: Battery powered, therefore the battery requires replacing when needed; suction cup may periodically need replacing; check for proper usages, as not all units are saltwater safe, and temperature ranges vary.
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Temp Alert Remote Sensor Digital Thermometers

Lifegard Aquatics Big Digital Temp Alert Remote Sensor Aquarium Thermometer
  • Pros: Not only an aquarium thermometer, these types of remote sensor units can have many features such as room temp and time displays, but most importantly include automatic temp setting high/low alarms; installed the same way as basic remote sensor units above.
  • Cons: Attached sensor cord can limit placement in aquarium, and black cord is visible; battery powered, therefore the battery requires replacing when needed; most often these types of units read either in Fahrenheit or Celsius, not both, so be sure to check which type you are buying.
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