Gallons/Liters
5ºC/9ºF
10ºC/18ºF
15ºC/27ºF
5 gal/25 L
25 watt
50 watt
75 watt
10 gal/50 L
50 watt
75 watt
75 watt
20 gal/75 L
50 watt
75 watt
150 watt
25 gal/100 L
75 watt
100 watt
200 watt
40 gal/150 L
100 watt
150 watt
300 watt
50 gal/200 L
150 watt
200 watt
two 200 watt
65 gal/250 L
200 watt
250 watt
two 250 watt
75 gal/300 L
250 watt
300 watt
two 300 watt

Instructions:
Subtract the average temperature of the room the aquarium is located in from the temperature you wish to maintain the aquarium water at. Find the size of your aquarium in the left hand column and move to the column that shows the number of degrees the aquarium needs to be heated. If the heating requirement is between levels, move up to the next larger size.

In larger tanks, or where the room temperature is significantly below the desired water temperature, two heaters may be required. Heaters should be installed at opposite ends of the aquarium to heat it more evenly.

Example:
Average Room Temp = 68 degrees F
Desired Water Temp = 77 degrees F
-----------------------------------------
Heating required =  9 degrees F

Tank Size = 20 gallon
Heater size needed = 50 watts

Please call us for help with aquariums over 75 gallons. 1-800-397-7238

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