Reef Aquarium Temperature Control
We do our best to help you guys, members of the reefing community enjoy your tanks and find new ways to explore the hobby. We do that by following the set up and progression of this 160 gallon reef tank. This week we are going to talk about temperature control. We will cover the different types of heaters, explain proper placement and demo a few different heaters accuracy and variation. We’ll also cover the temperature controllers, importance of calibration, chillers, fans and finish with our installation for the BRS 160.
There is a fairly big range that a reef aquarium can survive in, commonly anywhere from 76 to 83 degrees. Biggest advantage to running higher temperatures is increased metabolic rates which can increase coral growth and something most of us find desirable. There are however several disadvantages to higher temps with lower dissolved oxygen, the increased metabolic rate in fish means more waste, increased oxygen consumption,pest organisms grow faster and the closer you run to the edge of what is tolerable the faster things go wrong. During a power outage or equipment failure it is much easier and faster to experience a temperature related disaster at seventy six or eighty three degrees. This is why most of us shoot for seventy eight to eighty. As to an exact number you can find tons of polls around that show a pretty even distribution between seventy eight, seventy nine and eighty. I’d say most of those outside of this range are either advanced reefers with specific goals or those who don’t have the equipment to maintain a stable temp in the desired range.
One quick word on temperature stability. Basically any seasoned reefer who has one of those epic tanks full of really impressive healthy corals and intense coloration will tell you the biggest difference between their tank and the rest is the stability of perimeters like calcium alkalinity, salinity, nutrients, lighting and of course temperature. This really shouldn’t come as a surprise because almost every living organism thrives in a stable environment where it doesn’t have to constantly spend energy adjusting to changes in the environment or lack of elements necessary for biological function. While it is absolutely possible to maintain a healthy reef tank with unstable perimeters it’s the tanks that achieve stability that will most frequently see the most growth and best coloration. Pretty much all of us will need a heater to maintain a stable temperature in the tank. Even in warm states you probably frequently use an air conditioner to cool your home and even if you don’t you probably have some particularly cool nights in the winter. In either case your home will be cool enough you will likely need a heater.
There are four basic types of heaters common to the aquarium industry. These glass heaters controlled with a bi-metal thermostat which is basically a couple dissimilar metals that bend at different temperatures to control when it turns on and off. Heaters with built in electronic thermostats and controllers which turn the heater on and off. These electronic versions come in two basic types. One with external devices to measure the temperature and those with the thermometer built into the body of the heater itself. Lastly there are also heaters that have no built in thermostat or controller and require an external controller to operate properly. The bi-metal versions are the oldest design and I think the biggest benefit is the complete lack of advanced technology inside. The reason reefers don’t use them as often these days is because the contacts have a tendency to get stuck together over time which causes the heater to get stuck on and will likely be pretty devastating to the tank if you don’t have an external controller or catch it quickly. Even though some can be more expensive the electronic models are much more popular because most people believe they fail less frequently and provide a more stable temperature.
Because of all the reliability concerns related to aquarium heaters reefers have started to demand heaters without controllers and use higher quality external controllers of their own. You can use a controller designed for aquariums, something more industrial like the Ranco or a more feature rich full aquarium controller. At this point I think the full aquarium controller has become the most popular option because there are a ton reasons to own one and they have become so inexpensive it is easy to justify. For just over a hundred bucks you can pick up something like a reef keeper lite which is a lot more reliable and feature rich than any heaters internal thermostat. Some advanced controllers like the Neptune Apex have some pretty easy ways to set up email and text message notifications as well as easy to access advanced graphing. Within all these types you will find them all made out of different materials as well. Glass, various types of plastic and titanium. The titanium heaters are super popular because they don’t shatter like glass can. The titanium types come with built in controllers as well as with no controller as well. Plastic options are also less prone to shattering, One advantage to the plastic options is they can come in a variety of shapes. The Neotherm from cobalt aquatics is a good example. This heater is ultra-thin and fits almost anywhere in the tank which is why it’s one of my favorite heaters. To decide which one is right for you are going to have to weigh reliability, stability and accuracy with wattage availability and price.
For reliability your best bet is going to be to read customer reviews. Be prepared that basically all of them are going to have a healthy share of bad reviews so this is really a game of picking the best of what’s available. Make sure to actually read them rather than just look at stars because there is a big difference between a lot of complaints about it being off a degree or two which is super common and complete failure. To help provide some insight into accuracy and stability we performed a couple of demonstrations to give you an idea how some typical heaters perform. Break We used five one hundred watt heaters starting with a the Ehiem bi-metal glass heater, a digital glass version with the Finnex HPS, an analog glass with the Hydor, the flat digital heater with the Neotherm and a titanium HMO heater from Finnex. The goal here is to just give you a general idea of what to expect and not provide definitive proof one is better than another. This will hopefully provide some incentive to other reefers to do similar tests on their own heater and share them in the comments area below.
The most important element to me is stability and the size of temperature swings each has. We let all of the heaters run in a five gallon bucket with a small couple watt circulation pump and used a Neptune Apex to produce charts so you can see exactly how they perform. The biggest variance we found was with the Ehiem Jager true temp who had a pretty constant three degree variance as it cycled on and off. Three degrees is probably larger than most reefers would want for their reef tanks. I will note that this is one of the very few UL listed heaters out there so it is very likely one of the safer options and a solid candidate if you are going to use it on a controller which most of us will. The glass Finnex HPS had a somewhat consistent one degree which is inside the range of what I would call acceptable. Followed by the Hydor with a two to three tenths of a degree variance which is pretty impressive for an inexpensive heater. The Hydor is the only other UL listed option we demoed as well. The Finnex titanium was also very stable with just a couple tenths if of a degree variance. How-ever I think the most impressive was the Neotherm by cobalt aquatics. This thing is just flat meaning the water didn’t change temperature in any way detectable by the Neptune apex. I found that to almost be too good to be true so we moved buckets and tested it on a different apex temp module and got the same results. I think this is the only heater where I might consider using the heaters internal thermostat as the primary and my aquarium controller as the backup.
The other element we tested was accuracy. All of the heaters were set to eighty six degrees. I used a NIST validated thermometer certified to be accurate to four tenths ofa degree which is about as good as you are going to get without spending a fortune. Because it is NIST validated I trust it more than the aquarium equipment. The Hydor and Ehiem came in over three degrees high at eighty nine point two and eighty nine point three. The Finnex HPS was just over two degrees high at eighty eight point three. The Finnex HMO titanium and Cobalt Neotherm performed the best at just over one and a half degrees high at eighty seven point six and eighty seven point five. Moral of the story don’t assume any heater is accurate out of the box because it probably isn’t as close as you might think. Also don’t assume your aquarium controller is accurate out of the box either. I found controllers off by as much as six degrees. You absolutely need to calibrate your controller if it allows for it. Sadly if you read most thermometer details you will find them to state an accuracy range of plus or minus two degrees which is a pretty big range. Thermometers with tighter accuracy and certified to provide valid results are typically prohibitively expensive, often seventy to a hundred bucks.
Your best bet for calibrating is finding two or three cheap thermometers and averaging the results. This Oxo pen style, JBJ Digi temp, LaMotte armored, and lifeguard options are all around twenty bucks or less and suitable options. When you place the heater in your tank you want to make sure to place it in an area that would be very difficult to run dry to prevent damage to the heater, sump and potential fires. For in-stance the same area as your return pump is a bad idea. If you ever forget to top off the tank this area can easily run dry. Also if you use an aquarium controller with its own temperature probe make sure to place the probe in a different area than the heater itself, ideally in the tank itself or in a chamber before the heater. This will help you keep the temp more stable but also but also help with your alarms and notification system when your return pump fails or runs dry. If the probe and heater were in the same area it would only heat that single chamber but the controller would think the tank is fine. Placing it in a different area will let the controller know the tank is cooling down so you can do something about it.
Some of you may find the need to cool your tank. Maybe it’s hot in your home, you have a lot of equipment or lighting on the tank or you have very little evaporation all of which can cause the tank to overheat. The best way to keep the tank cool is to remove the offending equipment or replace it with more efficient equipment so you just don’t have to be concerned with this. Next best way is to increase evaporation by making sure the surface of the water is braking with a powerhead of some type and aiming a fan at the surface. This can be done on both the tank itself and sump. With the tank I think it is nice to spend a few extra bucks and get something low profile and quiet like the Tunze Aquawind. For the sump an inexpensive clip on fan like the Airking is the best option. If that still doesn’t do it you are going to have to consider a chiller.
I honestly try and avoid chillers at all cost because they are expensive, take up a ton of room and require a lot of power which you might not have available near the tank. A chiller is more or less an air conditioner so it also adds heat to the room and can’t be cycled on and off constantly because it would be bad for the compressor. You will inherently have a larger temperature swing each time the chiller turns on and off which I also find undesirable. If you do install a chillier I find the JBJ chillers to be the most reliable, among the smallest form factor and the quietest I have ever used. They also have a super helpful calculator on their site where you enter everything that is on your tank and selects the rightsize chillier for you which takes all the guess work out of something most people find pretty confusing. Once you have the right one you can either use your return pump, manifold or separate pump to cycle water through it and cool the water down for the tank. I would avoid sending water from your overflow into the chillier because I don’t want air, chunks of algae or rogue livestock getting stuck inside the chiller.
OK, time to install our solution for the BRS 160. If they came in the size I was looking for I would personally select the Neotherms from cobalt aquatics. My experience is they are the most reliable and stable of the heaters I have used myself, they are also ultra-low profile and easy to place. I am willing to pay the premium in this case. However they don’t come in the larger sizes I am looking for currently, hopefully they will rectify that in the not too distant future. Based on stability it was a close call between the UL listed Hydor and Finnex HMO but I decided to go with two three hundred watt HPS Finnex heaters. I may have to use three but we will see how these work out. The Finnex HMO seems to be the best mix of stability, price and accuracy. The titanium probe is also more robust than glass and in some ways safer. Coupled with that the reviews are more positive than negative so the choice wasn’t that hard. Because I would never trust my tank to any heaters internal thermostat without some type of back up I am also going to use the Neostat temperature controller on each heater which is the same controller that’s in the cobalt Neotherms. I will need one for each heater. It is a bit pricey which does make it hard to justify but I think it is the best option for something like this.
I will set the Neostat to eighty degrees and the heater’s internal controller to eighty two as a backup. Depending on how accurate each are when I check them with my thermometer I may have to adjust the temp of each to achieve the desired temperature for the tank and backup effect. The heaters are going to be installed in the filtration area of the sump and due to available cord lengths we are going install the temp probes in the return area. It is critical that the probes stay submerged at all times so we found a convenient spot to zip tie the Neotherm’s temp probes in place. To best honest on any other tank I would always install a full aquarium controller and use that to control my heaters. The reef keeper lite can control the heaters and a variety of other equipment for about half of cost of these two heater controllers which makes a complete aquarium controller in some form a no brainer in my eyes.
In this series we are going to show the individual stand-alone controllability options for everything,then install a full controller near the end of the series which is the reason I am using these Neotherm controllers now. A true aquarium controller will allow us to manage temperature to the tenth of a degree.Lets us set the second heater as true back up just slightly below the first one. This reduces the power cycles on the back up heater and makes it more likely will work when I need it. The aquarium controller can also operate a fan or chiller as needed as well as set off audible alarms, you could even plug in a light or something else to let you know if the tank is outside the intended range. You can also have it start powering down equipment like lights and unnecessary equipment to reduce heat. Last thing I am going to do is put a reminder in my calendar to replace these heaters in a year. In my never ending hunt of a high quality heater the only thing I have found that I think really works is buy what’s available and just replace them yearly before they fail me.