72 Hour Emergency Fish Tank Heater for $1

If you have tropical fish you need a 36-72 hour Emergency Tropical Fish Tank Heater. They only cost about a $1 to make (without the height adapter seen on the right). Use multiple Emergency Heaters for larger fish tanks. Keep a few ready for the next power outage.

One Emergency Heater will last approximately 36 hours running non-stop. It's designed for a minimum tank size of 1 gallon running only 50% of the time, up to multiple heaters running 100% of the time. Keeping any size fish tank's water around 80 degrees is possible during power loss with the correct number of heaters per gallon. Emergency Heaters will work with fish tanks 7" or taller.

The construction and use of Emergency Heaters should be supervised by an adult 18 years or older.

Step 1: Parts List

Parts Needed:

1) 8" x 2" Candle - You can get these candles just about anywhere. Dollar Tree has them (SKU#:167532) for $1.

2) 8" x 2" Wax Storage Jar- Other size jars will work, but 8" x 2" is the best. Once you make a few Emergency Heaters, you'll have plenty of these jars.

3) Large Cooking Pan - The pan should be at least 4-1/2" tall. Make sure the pan is big enough to fit both the candle and wax storage jar at the same time.

4) 1/2 Cup of Sand - It's free if you live in a sandy area or available at most arts and crafts stores for a few bucks. You'll need a measuring cup for the sand.

5) Tinfoil for the fish tank Emergency Heater top

OPTIONAL Emergency Heater Extender Parts:

1) 2" PVC Coupler - Any hardware store should have these.

2) Double Sided Tape - You will need a pair of scissors to cut the tape.

Step 2: Light and Mark the Candle

As the candle is now, it will float in a fish tank which is no good.

Light the candle. We need to remove all of the wax from the candle jar. Let the candle melt the first half by itself, then we'll use the pan with hot water to melt the rest.

Put the candle in the empty pan with no water.

Using a Sharpie pen, mark the candle about 1/4" below the edge of the pan.

While the first half of the candle is melting on its own, keep pouring out the wax every 15 minutes into the second wax storage jar until the melted wax is at the Sharpie pen mark.

Step 3: Heat Up the Wax

Now that our new candle has burned down to the mark, blow it out. Fill the pan with water (about 1/2" from the rim) and turn the heat to medium. Keep both the new candle (left) and wax storage jar (right) in the pan. You can pour wax into the storage jar every 15 min or so.

The goal is to get all of the wax out of our new candle and into the storage jar.

Step 4: Continue to Get All the Wax Out

It's sometimes helpful to tilt the new candle into the hot water to help the wax melt from the side. Just be really careful and don't let the candle fall into the pan of water. Be sure to ALWAYS use a pot holder or oven glove when touching or holding either of the the hot jars.

You will start to see a big floating ball of wax form in the new candle jar, let it finish melting completely.

Step 5: Remove Wick, Pour Out the Rest of Wax

Before pouring the remaining melted wax from our new candle jar, fish out the wick using a Q-tip or straw and set the wick aside.

Finish pouring the wax into the storage jar. Remove the new empty candle jar from the pan and wipe the inside with a paper towel as deep as possible.

Step 6: Add Sand for Weight

The reason we needed to remove all the wax is so we can replace the bottom of the jar with something heavier to keep it from floating.

Sand works out perfect and is usually free if you live in a sandy area. I found this pink sand on sale at an arts and crafts store for 50 cents.

Pour 1/2 cup of sand into your new empty candle jar.

Step 7: Add the Wick

Attach a garbage bag tie to the top end of the wick (the end you would light). Place the wick in the jar, centering the metal end of the wick on the sand. Bend the garbage bag tie over the jar to hold everything in place.

Place the jar with sand and wick into the pan and remove the hot wax jar. Be careful, use pot holder gloves!

You can turn the heat to low now.

Step 8: Pour the Wax Back Into the Original Jar on the Sand

Slowly pour almost all of the wax in the center of the jar on the sand. Try not to hit the sides of the jar with wax when pouring.

Pour all but about 3/4" of the melted wax, save this for later.

Keep everything heated on low until you see the wax make its way to the bottom of the jar through the sand. The air bubbles will stop at that point. Turn off the burner.

Remove your new Emergency Fish Tank Heater Candle and let it cool for 24 hours.

Step 9: Fill in the Dip

After the candle's first cooling period, there will be a dip in the wax on top. We need to fill that hole to level it off.

Heat up the remaining wax in the same or smaller pan and pour it on the top of the candle. You may have to repeat this step in a few hours if there is still a dip on top of the candle.

Step 10: Final Wax Layer: Optional

After I ran out of wax I noticed there was still a little dip on top of the new Emergency Heater Candle, so I filled it in with the melted wax of another candle I had laying around. It made it look cool too. [Optional]

The finished wax level should be between 2 and 3 inches from the top (which will also vary run time).

Step 11: The Heater Top - 1 Gallon Tank Example

To secure the candle's top we'll use a simple tin foil cover. You always want to have a top on a tank with Bettas, they are jumpers!

Use a double layer of heavy duty tin foil and make it the shape of your fish tank's top adding a 1/4 inch on all sides to secure to the tank.

Cut a hole the size of the candle in the center of the tin foil and add two pen size holes anywhere in the top, for air.

Place the top over the tank and wrap the sides down. Make sure the candle is about 1 inch above and out of the tank through the hole cut in the tin foil.

For larger fish tanks, a plastic cover with holes drilled may have to be used.

The water touching the hot Emergency Candle's glass is what does the heating. We want the "exhaust" from the flame/candle to never enter the tank. That heat is lost.

Step 12: Emergency Heater Extenders

If you need to raise the Emergency Heater for a taller tank, attach a 2" pvc coupler to the bottom of the candle. The coupler needs to look just like the one in the picture, having that center ring inside that stops the candle from going all the way to the bottom of the tank.

Cut one or two squares of double sided tape. Stick the tape on both sides of the candle's lower end. Leave the adhesive cover on the outside of the last layer of tape or you won't be able to slide it into the pvc coupler. Use enough layers of tape to make it really tight as you push the candle into the pvc coupler. The open slots between the pvc and candle will keep any air from being trapped in the bottom of the pvc coupler.

This will raise the top of your Emergency Candle 1-1/4" higher from the bottom of the fish tank. To raise the candle even higher, cut any length 2" pvc pipe and insert it in the bottom of the pvc coupler already installed.

Some Test Results using the Emergency Heater in this instructable:

Day one: 2:15pm - 10:15pm Run Time = 8 hours

Day two: 9:00am - 11:00pm Run Time = 14 hours

Day three: 9:30 am - 11:30pm Run Time = 14 hours

Day four: 9:00 am - burned out at 1:00 pm = 4 hours