Yeah, unless you are getting a sweetheart deal from your friendly neighborhood nuclear power plant / hydroelectric dam it's much cheaper to generate heat using natural gas than electricity.
what do you mean by "rigid sheets of insulation" is this the stuff inside the drywalls. And any ideas for it to hug the tank sort of? double sided tape is all i can think of.
Not sure I follow you. If you are raising the temp of your house by a couple degrees to heat a tank that's certainly more costly then using a heater in an aquarium no?
This is the same reason it's cheaper to run an electric space heater in a closed room than to raise the temp in the whole house with your furnace.
Yes, the unit of energy is more expensive via electricity, but that doesn't mean it would cost more in this applacation.
It's blue styrofoam rigid insulation. You should be able to get it at Lowes, Home Depot and any lumber yard. It comes in various thicknesses. 1/2 inch, 1 inch, 2 inches.
You should be able to get it roughly cut up so you can put it into your car. Otherwise you've got a 4 foot by 8 foot sheet to deal with. At home you can cut it with a utility knife, a hand saw etc. just be careful. And yes it is used inside walls.
The soft fiberglass insulation is more commonly used for insulation and that could be used inside your tank stand or where it can't be seen, maybe the back or side of a tank. As for attaching it to the tank, tape or silicone are two alternatives.