It all depends on how much the tank holds and the wattage of your heater I like to have 10 wattage for ever gallon so if you hVe a ten gallon tan you need a 100 watt heater also the temperature of you want will make a deference normally my 20 gallon tank can go from 46F to about 77 F in two hours
Yes, as long as you have a filter and a heater. Most breeder tanks have partitions that can be removed.
A heater can raise the temperature of a fish tank if needed
Less than 3 minutes! It shouldn't take that long
Tank water will slowly warm to ambient temperature. It will not get any hotter.
One can purchase a fish tank heater at various pet supplies shops. PetSmart, Petco, Marine Land, and Argos all have fish tank heaters for sale on their websites.
a big one!
Circulation
FIlter, heater, tank
If you have a heater, turn it off.
It is unsafe to heat anything smaller than two gallons. As long as your room temperature is reasonable (68-76ish for a betta) you should have no problems. If not get at least a two gallon tank and heater, one with an internal thermometer unless you want to monitor it 24 hours a day.
Usually there is a heater that warms the tank on purpose.
Most fish are around 78 degrees F.