Start the engine and check the voltage across the battery poles with a multimeter. It should read at least 12 volts. In Your Aquarium section to add heat. Particularly if it is winter time, covering the top of your tank if it is not already covered is important. Block off any hood vents that might allow heat to rise and escape.
Newspaper has amazing insulation factors.
Wrap the outside of your tank with a thick layer of newspaper to help retain some of the heat. In Your Aquarium Y ou can generate some heat in your aquarium with a hot water source. Anything that does not need electricity to do so will work. T ake a sturdy plastic container and put hot boiling water into it and cap it tightly. We used a thoroughly cleaned 1 gallon Clorox jug.