5 Gallon Fish Tank Heater

fish tank
An aquarium (plural aquariums or aquaria) is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants.
aquarium: a tank or pool or bowl filled with water for keeping live fish and underwater animals
Fish Tank is a 2009 British drama film directed by Andrea Arnold. The film won the Jury Prize at the 62nd Cannes Film Festival. It also won the 2010 BAFTA for Best British Film.

gallon
United States liquid unit equal to 4 quarts or 3.785 liters
Equivalent to 3.79 liters
The gallon is a measure of volume approximately equal to four litres. Historically it has had many different definitions, but there are three definitions in current use. In United States customary units there are the liquid (? 3.79 L) and the lesser used dry (? 4.4 L) gallons.
The Scots gallon was a Scottish unit of measurement of liquids that was in use from at least 1661, (possibly 15th century), until the mid 19th century. It was approximately three times larger than an Imperial gallon that was adopted in 1824.
(also used for dry measure) Equivalent to 4.55 liters
A unit of volume for liquid measure equal to four quarts, in particular

heater
A fastball
A heater is object that emits heat or causes another body to achieve a higher temperature. In a household or domestic setting, heaters are usually appliances whose purpose is to generate heating (i.e. warmth). Heaters exists for all states of matter, including solids, liquids and gases.
device that heats water or supplies warmth to a room
A person or thing that heats, in particular a device for warming the air or water
A conductor used for indirect heating of the cathode of a thermionic tube
fastball: (baseball) a pitch thrown with maximum velocity; "he swung late on the fastball"; "he showed batters nothing but smoke"

5
five: being one more than four
five: the cardinal number that is the sum of four and one
It is an irrational algebraic number. The first sixty significant digits of its decimal expansion are: which can be rounded down to 2.236 to within 99.99% accuracy. As of April 1994, its numerical value in decimal had been computed to at least one million digits.