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Although our kit included some key pieces of equipment, there are a few more that are vital to our success.

Most creatures we keep in reef aquariums come from tropical areas and require warm water, generally between 72°F and 82°F. The sweet spot is around 78°F. To achieve this, we need a good, reliable heater that is also appropriately sized for our tank.

Traditional, common heaters are made out of glass and have a mechanical means to control temperature by turning on and off. Although you can use one of these heaters, they are not only fragile but also prone to failure, so I don't recommend them. There are many stories of these heaters getting stuck on and making an unpleasant soup in the tank or breaking and leaking voltage into the tank, zapping the inhabitants or anyone else who sticks their hands in the tank.

I prefer titanium heaters or the Cobalt Neo-Therm which is not only sleek but very durable and extremely accurate. It displays the current temperature as well as the set temperature and, when the two diverge, its light blinks to get attention. It has a digital thermostat and some form of thermal protection circuitry which I can't attest to since I've never had one fail.

It is a bit more expensive than other heaters, but I believe it's worth it. I chose the 100W model since it is rated for tanks up to 29 gallons.

The Best Way

For this tank, I'm going to use a single heater and let it control the temperature. But that is, in part, because I trust these heaters, I have a spare in hand, it's summer time and I will be near the tank most of the time.

Arguably the best way to heat your tank and protect your creatures is to use a heater controller together with two titanium heaters.

Here are some of the advantages of this setup:

  • The heater controller can be far more accurate than the thermostats in some heaters, which means smaller temperature swings in the tank. Some allow you to configure a threshold from the target temperature.

  • The controller has a separate temperature probe, which can be placed somewhere else in the tank whereas a normal heater is measuring the temperature of the water around it.

  • You can configure a high temperature cut-off, so when the heater sticks on and the water gets too hot the controller will cut the power to it - preventing the deadly soup.

  • You can use it with two heaters, so that one will keep things alive if the other fails.

  • Some have audible alarms that will bring you to the tank when something goes wrong.

  • The titanium heater elements are durable and don't have an internal thermostat which makes them more reliable.


If you live in a very warm climate or your tank will be in a spot where the ambient temperature is high (like your garage), you may also need a chiller to bring down the temperature of the water.

A chiller is like a small air-conditioner, but for water. It requires a pump that brings in water from the tank that is then cooled before being returned to the tank.

If you think you need one, do a bit of research and find one that is appropriately sized for the water volume of your tank. There are a few leading manufacturers of aquarium chillers and you can often get good deals buying a used one.

In some cases, we can get away with a small fan blowing across the surface of the water to lower the temperature one or two degrees. This is called "evaporative cooling".


Although the heater I chose shows you the current temperature of the tank, we're going to put it in the sump where it will be difficult to see, so we need something else. I also like having an audible alarm to alert me when the temperature is off.

So, I will be using an InkBird digital thermometer that I had left over. I can stick this to the wall near the tank and always see the temperature. I can also configure low and high temperature alarms via Bluetooth.

There are many cheaper alternatives and the Bluetooth functionality is definitely overkill, but I suggest you get something similar. It is important that you choose something that has a saltwater-safe probe: metal probes won't do.

I personally despise the stick-on thermometers. They are not very accurate and are very hard to read. Plus, they affect the aesthetics of the tank and leave a glue residue if you ever try to pry them off. They also get in the way of cleaning the glass.

Floating glass thermometers are OK, but they're fragile and breaking one can harm the tank.



First, we're going to setup the thermometer.

  • Give the probe a quick rinse and then dry it.

  • Use the provided suction cup to place the probe in the tank. In my case, I will place it in the sump, near the return nozzles.

  • Place the readout somewhere you can see it. You can use velcro with double-sided tape.

  • Configure it to alert you if the temperature gets below 74°F or above 82°F.


Setup for this heater is very easy.

  • Take it out of its packaging and give it a quick rinse in tap water. Then dry it.

  • Put the two suction cups in the mounting bracket.

  • Stick the bracket into a sump compartment where it won't interfere with anything else and slide the heater into the bracket. Make sure it is completely submerged.

  • Leave it there for at least 15 minutes before you plug it in so it can adjust to the current temperature of the water.

  • Plug it in, making sure the cord has a drip loop.

  • Now, set the temperature to 78°F by pressing the button on the top of the heater until the light reaches the mark. Once you let go, the set temperature will be shown by a green LED and, if the actual temperature is more than 2°F off, a yellow LED will blink indicating it. Mine was set to 78°F out of the box, so I skipped this step.

  • Confirm that the actual temperature indicated by the heater is somewhat close to the one indicated by the thermometer. Always cross-check.

  • Come back in a few hours to make sure things are working properly.

As soon as we start warming up the water, it's going to start evaporating. Let's deal with that next.