How long should a heater take to heat up a tank ?

[fishguychris]

How long should a heater take to heat up a tank ?

 

[NeverFadeAway86]

Depends on how big your tank is

 

[FreshyFresh]

That'll heat a 10g pretty quick.

Seriously though, it depends on how cold the water is, the ambient temp and the water volume. You need a bit of wattage to maintain more than 10-15deg above ambient temp.

 

[smitty]

There are several factors. How cold is he water, the size of the tank, and the temperature of the room, and water circulation.

 

[Rbishop]

And if the tank is covered or not.....

 

[tanker]

Is you tank too cold?

 

[Gregg]

Here is a formula I use:

As for heating requirements, I recommend 25 watts of heater for every 10 degrees of ambient temperature per 10 gallons you need to raise your aquarium temperature.
EXAMPLE: If your home is 68 degrees and you have a 40 gallon aquarium, to reach a temperature of 78 degrees you would need a 100 watt heater.

Quoted from here;
http://www.aquarium-pond-answers.com/2007/01/aquarium-heaters-preset-vs-non-preset.html