Look at the front of the filter you should see a little red light come on.
Top fin 50 watt aquarium heater instructions.
Non preset aquarium heaters are less expensive than their preset counterparts often as little as half the price.
This is all the instruction paper says about this matter i quote.
Turn the temp seeting knob clockwise a little bit till the heater turns on.
Large aquariums lose heat more slowly than small tanks allowing you to buy a heater with as few as 3 watts per gallon.
When you do the heater just started to heat.
An aquarium heater without an adjustable thermostat also means that the heater cannot be adjusted to account for differences in power stability or for age of the heater and components.
Choose a submersible aquarium heater that provides 5 watts per gallon.
Ta50h 50w ta100h 100w ta150h 150w ta200h 200w and ta300h 300w 120 volts 60 hz 300149903 feb2017.
For example a 20 gallon tank would require a 100 watt heater.
If it is set to 28 c the heater will heat the water to 28 c and then will switch off when that temperature is reached.
And canadian safety requirements.