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How to Make a Fish Tank Heater

| Updated September 26, 2017

Things You'll Need

  • 4 10-inches long 2-by-4s

  • Four nails

  • Hammer

  • Glass measuring 10 by 10

  • Rubber mat or metal

  • Coiled copper piping 15 inches long

  • Fish tank hose

  • Hand saw

  • Duct tape

In 1981, the first solar water heater was patented, but it was the hot box that was the prototype that gave way to using solar energy to create heated water to millions of people since 1982. After years it became apparent to the everyday man that solar heating compared to coal or wood was much cheaper. In our world today we can apply these techniques to heat almost anything we want for a decent price.

i sun and window image by cemil adakale from Fotolia.com

Set up your aquarium near a natural light source.

Nail the four boards together to create a square.

Cut two notches out of one piece of the wooden square, using a hand saw. These are where the copper piping and hoses will come out.

Lay a rubber mat or metal on top of your wooden square, and duct tape it down to the square. Both rubber and metal attract heat.

Flip over your wooden square. Lay the copper piping in the box so both ends come out of the notches in the wood.

Set the glass on top of the wooden square, and duct tape it to the wood.

Cut your hose in two separate pieces, long enough to connect to the pump.

Connect the pieces of hose to the copper pipe, and apply silicone around them to be sure the water does not leak. Place a small layer of duct tape over the silicone.

Connect one of the open ends of the fish tank hose to the pump and connect the other open end to what is sending the water out of the tank up into the pump.

Set you new solar panel in a well-lit window behind your tank.


  • Give the panel time to heat up before starting your pump back up. Depending on your tank size, you may need to build a bigger panel. Remember to let the fish adjust to the water by leaving them in their bags in the water for at least an hour.


  • Keep an eye on your tank thermometer to ensure it does no overheat.