The $27 Purchase That Saved My Tank: Aquarium Heaters

Updated: Sep 27


Eheim Jager Aquarium Hearer


Last week, I got a series of alerts from Apex Fusion. Every five seconds a notification was coming in. Alarm on, Alarm off, Alarm on, Alarm off. My phone was buzzing, my watch was vibrating, and—since I’m stuck in my house for the foreseeable future—alerts on my home computer kept dinging.


Something was wrong. And my tank had FINALLY been on auto-pilot. I thought I would be worried free for at least one week.


With trepidation, I opened up the alarms on Fusion. I expected to see my Alkalinity was off. (I just had replaced my Trident because of Alkalinity test fails). What I saw was completely unexpected.



Apex Fusion Temprature Alarms


My water temperature was dropping. The system was struggling to keep my tank at its normal 78. In fact, my temp had dropped to 74.


Fortunately, it is an easy and cheap fix. Just get new heaters. And, in actuality, I always plan on getting new heaters once a year. Here’s why.


The Importance of Water Temperature


Before getting into why I plan on replacing the heaters every year, let’s first refresh why temperature is important. It is pretty basic, really. If the temperature is too high or too low, then the necessary zooxanthellae algae will die. This is bad. Corals need zooxanthellae to survive. It is actually the absence of zooxanthellae that expose the corals’ white skeletons resulting in the phenomenon known as “coral bleaching.”



Coral Bleaching Coral Skeleton


Higher temperatures also affects the dissolved oxygen level. It is essentially an inverse relationship. The higher the temperature, the lower the dissolved oxygen level. This is bad news for saltwater tanks since marine animals generally require a higher level of dissolved oxygen than their fresh water counterparts.


Controlling Temperature


There are all sorts of articles and forums out there about the ideal water temperature, but the consensus is between 75-78 degrees Fahrenheit. Keeping the temperature in that range is actually fairly easy these days. A simple controller can do the trick. As mentioned, I use my Apex and the Fusion app to control it. But you don’t need an Apex to do that. In fact, the pico jar I started in my office (I am super dreading being allowed back to work after this pandemic; either Xenia will have taken over my entire office or I will have some serious glass cleaning to do one weekend) uses the $35 Inkbird controller. They work the same in theory: you set a low point that kicks the heater on and a high point that kicks the heater off. I have Apex programmed to kick my heater on when the temp falls below 78 and shut off when the temp reaches 79.


Yearly Heater Replacements


So why plan on yearly heater replacements? Because your heater is your weakest link. It is the piece of equipment that is most likely to fail. It will fail. No heater will last forever. That is exactly why the manufacturers only generally provide a 1-2 year warranty on these heaters. And I am a firm believer in Benjamin Franklin’s old adage that one ounce of prevention is worth a pound of cure. Don’t believe me? Wait until you have a cyanobacteria or green hair algae bloom before you work on your phosphates and nutrient export. You’d rather have spent the 30 minutes a month on maintenance to prevent that rather than trying to clean up, right? Yeah, I thought so. Think of your yearly heater replacement as the equivalent of your 30 minute monthly maintenance.


In fact, heaters are so prone to failure that many reefers, myself included, actually have back up heaters. I have a second heater that I program to turn on if the temperature falls below 75 degrees. That way, if my main heater fails, I still have something in there to keep the heat going.


In an ideal world, I would have replaced my heaters before my Apex started alerting me. But the truth is, it has been about a year and time for a change anyway. And while I could go into Apex and look at the data to determine if my backup heater failed as well as my main heater, I didn’t bother. I bought both heaters at the same time, they will likely fail around the same time. Even if the backup heater isn’t broken now, it likely will be within the next few months. So I just bought two new one.


What Heater to Buy?


Ok, so I’ve convinced you to replace your heaters. What heater to buy? You’ll find passionate votes all over Reef2Reef. Under my system, the choice is easy: The most reliable heater that is on sale at the time of replacement. You are going to replace this in a year anyway. You have your redundancies set in place. No need to spend tons of cash on a heater you are going to replace in 12 months. Just get one from a reputable brand that is within your budget. Save the cash for that coral you were eyeing. Avoid the no name brands from eBay or AliExpress and you should be fine. In my case, I went with the Eheim Jager that I picked up for $27 from Amazon.


Final Thoughts


There are so many tips and hacks for controlling heating. Some people use two heaters of the same power for both their main and their back up. Others use two smaller heaters, either of which would be insufficient to heat the tank on its own, but run them the same time. Some use the heater’s built-in thermostat and others deliberately set the heater higher and use the controller to keep the temperature stable in order to build in another redundancy.


Do you have tips or tricks for your heater? Let us know in the comments! Do you have a heater question you want answered—maybe looking for step-by-step instructions on how to program your heaters? Ask in the comments or feel free to email me.


Happy Reefing!


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