Choosing An Aquarium Heater
Aquarium heaters are necessary when the room temperature is too cool for fish or the day to night time temperature fluctuates allot.
Most tropical fish require a consistent water temperature of 76 degrees Fahrenheit.
Do some research on the types of fish you want to keep some species like Discus like 82 F to 86 F where as other fish like neons like 72 F to 75 F.
When choosing an aquarium heater remember, you really get what you pay for. Cheap aquarium heaters have thin glass tubes and inferior internal components. They break easily and can get stuck in an on position, over heating your fish tank and killing your fish. Higher end heaters very rarely stick in an on position and have thicker higher quality glass tubes.
Allot of aquarium heater manufacturers do not warranty the glass parts of the heater. So if you purchase a cheap low end heater, be prepared to possibly be purchasing another heater in under a year.
For aquariums up to 100 gallons you will need approximately 3 to 5 watts of heat per gallon. Example: 5 watts x 30 gallon tank = 150 watt heater.
Larger aquariums usually have different heat requirements depending on the filtration system. If your using a wet dry filter
the main return pump will produce some heat, so you won't need a large heater. Or in some cases no heater at all.
Higher quality heaters are usually more efficient, so check the manufacturer's recommendations. In hot climates a heater may not be necessary. Just remember if the daytime ambient room temperature is 80 and the night time ambient air temperature is 72 you will need a heater to keep the aquarium temperature stable.
Three to Five degree Fahrenheit temperature changes over the course of a day can cause the fish to get very sick
When adding a heater to your aquarium let the heater sit in the water for a minimum of ½ an hour before plugging it in. this ensures that the heaters glass tube is the same temperature of the water helping to prevent thermal cracking and the loss of your heater. Also if you ever need to remove your heater from the water unplug it for at least ½ hour.
I have had good luck with the following brands of heaters.
Eheim Jager Heaters
These heaters have a 2 mm thick DURAN laboratory safety glass tube which is shock resistant and almost twice as thick as most heaters. A bi stable thermostat that is accurate to + or - .5 degree accuracy. They also use chrome nickel helical heating coils for even heat distribution. Its completely water proof and very easy to adjust. If the heater comes out of the water to much it also will shut off, helping to prevent the glass tube from shattering. I rate this heater as the best.
These heaters are water calibrated and very easy to adjust the temperature. They have a double seal and are certified accurate to with in 1 degree Fahrenheit. I don't think the glass is as quite strong as the Eheim Jager heaters, but compared to some of the other heaters out there I still rate these as very good.