Why No Heaters?

Heaters are one of the most misunderstood, oversold, dangerous, and generally useless pieces of aquarium equipment sold.  The average saltwater tank does well between 72 and 78 AVERAGE temperature.  A minimum of 65 and a maximum of 86 I personally set as limits.  As long the temperature returns to the Average range, both fish and corals can handle extremes.  Running your aquarium without a heater in the average home usually keeps it from 72 to 78.  Pumps and lights produce heat.  Summer weather, enclosed stands and canopies present cooling issues.
So you might wonder if and when you need a heater.  When your aquarium has a difficult time staying at 72 for roughly 18 hours a day.  If your tank is in a basement or in an uninsulated space or you might have your filter in one area and your tank somewhere else, a heater might be necessary.  The safest way to set up a heater on a timer is to have it come on for 1 hour every 6 hours – 1 on 5 off  1 on 5 off  1 on 5 off etc.  Set the heater at 78-80 and plug it into the timer.
WHY do all this?  Heaters crack, leak in water, short out and run at full power cooking your tank.  Sometimes they catch fire, explode or melt down poisoning the aquarium.  Even when temperature is set low and plugged in heaters are not truly off.  After 19 years in  business I’ve found that heater failure is the number 1 reason for total tank destruction.


Thermometers simply measure heat. Measuring tank temperature is generally ignored by too many people.  We recommend glass laboratory thermometers available in centigrade, Fahrenheit or both under $10.  Beware digital models.  Low batteries cause incorrect readings.

Interesting facts

There are 3 scales: Fahrenheit, Centigrade or Celsius and Kelvin

0°K = -273.15°C = −459.67°F is known as absolute zero.

The freezing point of water at sea-level atmospheric pressure occurs at 273.15°K = 0°C = 32°F

Centigrade and Fahrenheit have only 1 point where they are equal -40°F = -40°C

Body temperature 98.6°F = 37°C

Room temperature estimate 20°C = 68°F

1°K = 1°C = 9/5°F

In science there isn’t a definition for “cold”, just an absence of heat.

Share This