Start by creating a list of the wattages of every components, and how many hours a day they run. We can start working it out from there.
What an even better thing to do, is to do that for everything in your home, and you will gain a better understanding of how much power you are using.
Oh and heat pumps use a lot of power... sure they get marketed as being efficient, they are... but they still use thousands of watts. If its a big one, and it draws say 4kW, then you can bank on almost $1 an hour when you run it. 4hours a day, over a month adds up to $120 quickly.
With our tanks lights and heating are the biggest component... the rest is pretty neglegible.
To give you an idea, my 200L tank with a 200W heater, a filter that draws 25w and 60W of lighting costs around $3 a week on power. and that is sitting at around 26degC