Heater is very unpredictable with fairly large swings in temperature, then had the same issue where all of a sudden the heater wouldn't turn off and just kept heating my tank about 1°/day until it got to 83°F and I had to put my cheap WC heater in my DT. Tried calibrating during a mixing session and no matter what it won't stop heating. This is clearly a common issue for this model and considering my half the price WC heater is doing better I'd say you can find better options than this one most anywhere.

Was quoted by a BRS employee that I need 2 150 watt heaters for my 125 with 40 gal sump. Way under kill, temperature actually drops instead of rise. Maybe two 150's for a 90 gal.

Set and forget,don't think so,wake up to 86 degree tank water once or twice and these go in the trash

Even after calibration doesn’t show or hold correct temperature. Waste of money

Heater was a little tricky to setup. Unlike other heaters I’ve used where you can drop it in, set it, and forget it, this one started to heat my water without me wanting it to. Apparently the heaters come calibrated from factory, but when I placed this one in my aquarium with a set temperature of 76 degrees, it started heating my water until it got to 80 degrees and would’ve kept going had I not unplugged it. After watching some setup videos and tinkering with the heater, I was finally able to get it to stop heating at the temperature I set it to. Also, this heater needs to be set where there is a good flow of water.

My experience with TWO virtually new heaters, 100W and 125W is they are incredibly inaccurate. Just trying to use regulate them for use in a salt water mixing station was so frustrating I pitched them both. Despite being turned to their lowest settings they'd continue to heat in water 10 degrees above that setting.

Ordered 50W in Sept 22, failed today June 28. Set to 75 (to maintain 78), heats to 88.2 then internal limiter kicks in, I assume. Was working to .5 holding temp until now, but without the Inkbird, my fish would be toast right now... Back in the 90's Jager was a great product... not anymore.

I have been in the hobby for over 10 years and have tried these a couple of times and EVERY SINGLE time these things do NOT hold anywhere near the set temp. They overheat the likes of which I have never seen. I set them to 75 and they exceed 79.5 degrees. It's like there is no internal thermometer that even remotely works. Unfortunately I have to give this a star in order to post a review.

Just your basic heater, didn't need fancy, this works just fine. Will be purchasing two more for my two IM 15 gal cubes I have coming!

I purchased 2 of these 75W models around the same time. About 6 months of use on both of them, and both heaters have the same issue. The temp slowly starts rising, and trying to adjust the temp setting down just makes it go even higher. I'll keep them for WC containers, but will be finding a new heater for DT.

I’ve been using these for years and trust them not to fail. With that being said the calibration ring is not very accurate. For this reason I use it in conjunction with a separate controller.

I have the 200W heater in my 30gal sump for my 75gal display. Brought my tank up to temp quickly and has been working great ever since. I was nervous with shipping. The box was smashed, then the heater box was smashed and finally the plastic ring protecting the glass heater was lightly broken from the impact. The glass heater was unhurt and works great. Not the fault of BRS for the damage. But if you have aggressive shipping company employees, the heater can take the abuse.

I've had a 100W on my Nuvo 20 for over a year now and it keeps the temperature very stable. My daily temp swing is .8 degrees, granted it is hooked up to my Apex though.

I have used these heaters for over a decade. I’ve used them in both freshwater and saltwater tanks and they’ve always performed well. It can be confusing to calibrate but with some trial and error I’ve figured it out. I find now that they work great with a heater controller like an inkbird.

They're relatively cheap and keep my tank warm - just what I need. You can adjust the pieces at the top to calibrate it to the scale, but really, as soon as I hone in on the temp I need it at, I just leave it. Just make sure to pay attention to the lengths - I got the 200W and it now heats my water change tub because it's too big for my sump; I replaced it with two smaller units, which is also great for redundancy in case one goes out.

Bought the 200W for my 100 gal mixed reef tank. It heats the tank steady and effectively. We keep our house around 65 F at night and 70 F at day during winter months. Gave it 3 stars because the temperature setting dial is off even when you use the compensation dial. I keep my tank at 76 F and the dial reads 80 F and that is with the compensation dial maxed out to the corrected side. Also, the dial is hard to adjust, especially after it has been in the tank and has some slime on it. All in all though, it does its job. Just make sure you have an accurate way to measure tank temperature while getting it dialed in.

Great heaters for the price. I love that they can be calibrated to the correct temp if necessary. Have proven to be reliable to me over the years Only downsize is the length of the heater, larger wattage heaters can be hard to fit into traditional sumps. I am using 2 - 100W heaters on my aquarium as they fit better within the sump of my aquarium compared to a single 200W

Stopped heating well at about 1 year. Contacted support and got a replacement stat. Other than that, like any other heater with a dial adjustment, always reference it to a calibrated thermometer and don't trust the markings on the heater itself and it'll be fine. The larger heaters can be a little large so measure correctly.

These can handle a much bigger tank than most other 300W and are a much better price. Just make sure you have them on a temp controller as after 5 years or so sometimes they jam on. So temp controller on the outlet is a must.

The heaters work... I have three of them but the scale is a joke. My last one purchased two months ago is at 73 degrees Fahrenheit and is heating my tank to 78 degrees. the scale adjustment on the rear can't go any further to compensate for the discrepancy. I use a Milwaukee thermometer with a probe and totally disregard the numbers at the top.

I've got 2 of these in my 110g system running off an ink bird controller. After calibration and setting their internal thermostats to 79, ink bird to 78 I'm on cruise control for my cold winters in my uninsulated house.

Had this for a year hooked up to an inkbird temp controller and have had absolutely no problems out of it. Good piece of kit.

Didn't work right out of the box. The calibration ring wouldn't even turn far enough to be in line with the actual temperature. The heater continued to cycle on, heating the tank over 80 degrees, even after turning it all the way down. There appears to be no support for this heater either, so you really are taking your chances.

I have had a ton of these over the years, several for many years, and they are rock solid. I have one that is five years old that I use to mix saltwater. I'm not concerned about a failure in my mixing container. So where's the but? There are two major issues with these. One is the size. Finding a spot to put some of these monsters in a sump can be a bit of a nightmare. Two is the temperature variance. I'm not talking about the set point being off from the actual temperature. They can be calibrated and even if they couldn't I could care less if the set point is 84 and it's true set point is 78. I'll set it at 84 and understand I'm really saying 78. It's the swing. Some of them have been upwards of two degrees. I usually use two undersized heaters to blend this out, but still...

Over the years I have jumped on some of the latest and greatest technological advances in heaters and controls only to be disappointed every time. I have many tanks on independent systems and need heaters that are reliable, long lived and pretty stable when sized appropriately. I continually find myself going back to Eheim Jagers. You can spend WAY more but in my experience your are not getting anything that WAY better. I definitely recommend!

Bought multiple heaters because they were highly reviewed but they keep failing. So now i have to say that these heaters are awful. Do not buy one get something else.

Haven't had any issues in over a year. Just bought 2 more. I use an apex to control the temp so I can't say one way or the other on the calibration of them. I set them to 79 but have my apex turn them off at 78 and haven't had any trouble.

I got the 250w for a 105 gallon system. Seems to be doing its job!

200 watt version failed off after ~1 year. Though there is a 3 year warranty...

Heater works great no problems in two years.

I have these heaters in multiple sizes. These seem very durable and do the job with no problems. So far I've been using eheim for about 7 years and the first one i bought is still heating by freshwater aquarium.

I see there are reviews that have said the temps are all over the place but I have not had that problem. I use this as an emergency heater (200 watt) and its controlled by the Apex. Showing 190 Watts draw right on the money compared to the Finnex which is a solid 50 watt lower than advertised. So whether the temp is all over the place (it isn't) it still has an external back up to cut off the power at a certain temperature.

I know that there are very few heaters that get much love from reefers, but I hoped that these Eheim Jagers would be better. I bought four - two 75w for my 40g, 1 50w for my 10g q tank, and 1 25w for acclimation, dripping & dipping. The physical appearance and quality seem excellent. The materials seem firm and sturdy. After letting them come to ambient water temp, unplugged, for an hour I set them to 77deg. 8 hours later, they were all over the place. Same 24 hours later (new tanks, no fish/coral, so no big deal). Long story short, All were off by 4-8 deg F. Two of the four re-calibrated easily. The other two - off by 8 deg F - are so far off that they cannot be calibrated. I'll live with them and adjust accordingly, but I will not be buying them next year when I replace my heaters.

I gave this 3 stars because when it's working right it seems to do fine. However, I have always had a hard time adjusting the temp and calibrating. I have to use use a very firm grip on the element and on the temp control knob to adjust it. When calibrating in a 5 gal bucket and checking against a digital and old school thermometer it was constantly fluctuating and would not hold steady. This occurs on BOTH heaters so doesn't seem to be a fluke necessarily. My next purchase will be a different brand.

Bad out of the box. Overheats tank consistently. Don't turn your back on it. Calibration ring cannot move far enough to calibrate to current, verified temperature. Tank was up to 81 degrees and I had to turn the heater to 72 just to get it to cycle off. This happens constantly. These used to be great heaters in the 90's.

I've had a couple of the 300 watt versions of these. I really like the calibration and the switching mechanism that make it more reliable. However, the first one started fogging up with moisture on the inside after 4 months and the second after 9 months. They both still worked, but I didn't want to take any chances with it seeing water in there. Disappointed that this happened as I hear good things about this heater. Not sure if this is more likely with the larger models are not.

30 gallon reef tank: I set it to 75 and noticed my tank running at 84! Corals not happy. Cooled my tank to 78 and set it 70 and my take ran up to 82... can’t use!!!

Really like this heater for the money, mine was off about a degree when I calibrated it before putting in my tank.. doing great job keep temperature stable.

Works great. Easy to use and set up.

Ordered a 50 watt heater, didn't use it for a month. Finally went to use it and the temp control is way off. I have to have it set to 73 and the 10 gallon tank is 80 degrees in a 71 degree room. Without the heater the tank is usually only 1 degree hotter then the room for my small tank. Not reef recomend.

I have been using these heaters for the last 6 years. From 75 W 125 W and 300 W heaters, once set they hold temp very stable. I don't try to set the calibration ring because getting the ring to match a given temp is to hard to determine. But once you set the temp of your tank, it doses a very good job of keeping the temp stable., which is most important to me. My pair of 300 W heaters have been going strong for over 3 years now ,with another pair waiting as back ups.

These are great heaters and definitely worth the money. Only issue i have, as also mentioned by others is that they are very long heaters. The 150w is over 12 inches long and wont fit vertically in a 20 gallon long. So if your using a 20 gallon long for a sump you have to fit them horizontally or at an angle. I also have the 300w heaters and they are also long at 19 inches (They just fit Vertically in a 55 Gallon). I really like the calibration dial at the top where once your temp is set you can mark what temp it is set too. Reliability wise they are pretty robust in comparison to other cheaper models

Heater works great, keeps temp stable, couldn't ask for more

I should have remembered when I was shopping for a 200 watt heater at how large these are compared to others. I wanted a 50 watt for my 12 gallon nano. I knew these were reliable so I ordered one. It really is a great heater, it's just so big.

Got my 300 W heater with my used tank so no idea of it's age, but did an adequate job for the 92 gal tank. A month after moving it to a newer 115 gal, it couldn't keep up and temps swung up and down, mostly down. Checking power monitor of Apex EB32 found the heater was cycling at ~50% duty cycle over a 50 minute cycle time, 25 on, 25 off. Not a terrible fallback failure mode, just not enough to keep the tank up to temp, but unlikely to act like a stuck one and cook the tank either. Replaced with the same Eheim 300.

Use 2 of the 300 watt heaters in my fish room and they work great! Just check the lengths as the big ones are quite long and the stiff cording adds a bit to the room needed in the sump.

Had them for over 3 year 3 of them 2 tanks no issues I do have a neptune controller running them so I cant attest by the thermostat.

I have a few of these heaters in various sizes. They all have good precision and I like that you can calibrate the dial to the match the value read by external thermometers. One of the heaters has stuck in the on position a couple of time. Luckily it is connected to an aquarium controller which turns off the power to the heater when it does this so I can prevent if from killing my livestock. Tapping the side the heater a bit fixes the thermostat for a while.

I bought this hoping for it to heat the water, but it never turns on anymore and I think think it's broken. I haven't seen the orange led on in a few weeks to be honest. I don't like the calibration feature because truly don't know how accurate it is even with another digital thermometer. I'd recommend purchasing another brand. I'm also willing to admit that maybe I didn't buy the correct size for my tank and it's my first heater ever, so I'm still learning.

We have two 75W heaters in quarantine tanks, two 300W heaters in our 300 gallon display tank and three more in our 3x125 gallon mixing tanks. Haven't had an issue with any of them!

Arrived DOA. Not worth the hassle of shipping it back. The package was in excellent shape. Buy something else.

Fantastic product. Amazing quality and the only heater I purchase.

I like this heater but it doesn't fit in my sump. The cord is stiff so take an extra few inches into account to fit it in your tank. I now use it to heat water during water changes.

Bought this heater brand new and it did not work. Their customer service was horrible so I returned it and went with a different brand. I wouldn't recommend eheim, I've had an issue with their auto feeder as well.

I have two of these a 300 watt and and a 125 watt. The 300 watt is accurate to within 1 degree, the 125 watt is within 2-3 degrees. I simply love these heaters they are so easy to use, just plug and play. Will definite be buying more when I need them.

Easy to use. Love that it is dependable. Would tell others to buy it.

Absolutely without a doubt my go to heater. Easy to calibrate, dependable to use. I would 100% recommend this to anyone.

I like this heater. I use a 300 watt Jager and find that it does a good job of heating my tank and is reliable. Good price here at BRS as well.

TIP: Split required heating wattage between two heaters and run them on a controller

Extremely stable temperature. Works better than expected, and really easy to calibrate!

My Jager never was able to run without a 4 to 6 degree fluctuation, so I had to get a thermostat and not use the sub par thermostat. However, it is built very nicely, so once I got a thermostat, I had no problems. This is not a deal breaker because most heaters should be run on a reliable thermostat, anyways, to avoid failure.

This heater is spot on after calibration. I use one in my sump and I have another one I use in my salt mix container. Always spot on

As I unpacked the 300W Large Heater, I was worried damage had occurred during shipping. To my delight, I saw the packaging ring had done its job with three broken prongs, but no damage to the Heater itself. It came preset to 79 degrees F and after 48 hours I checked it with my Fisher Scientific Thermometer to be accurate within 0.2 degrees. I am satisfied with the purchase and will probably buy another one in the near future.

I have four of these heaters... two in my sump which are controlled by my Apex system... one in my mixing tank (just using its own thermostat)... and another that is a spare except for when used in a quarantine tank. The ones that are controlled by the Apex keep the temp within 0.2 degrees F. The one in the mixing tank reads a bit low (i.e. the water is slighter warmer than the setting on the dial when checked with an external thermometer... but works fine) I have the same complaint as others however... they are fairly long and you need a larger sump for them to fit nicely.

I hate this heater my QT tank heater from Petco is far more accurate than this junk, on every setting I wait 12-24 hrs for re-adjustment and it fluctuates 2-4 degrees, I had it set to 78 24hrs ago and this morning water temp at 82 and claiming so I re-adjusted and lowered to 78 again waited 1hr and the thermostat still is on so I lowered again some more and forgot about it and went to work, so I am hopping I don't get back home to a aquarium full of dead fish. This should not be so complicated for a simple heater and for less than $30.00 you have the risk of loosing everything.

About a year ago I went through several heaters before stumbling upon the eheim jager trutemp. I purchased a brand new 200w jager trutemp for my 75g reef tank and I was having problems with the heater fluctuating temps drastically. After emailing the manufacturer they promptly sent me a brand new replacement and I've been using it every since!

Used in Mixed Reef 120G, Temperature variation of ~1F using my Apex Controller, no problem and work as intended. I wish they had a shorter design as it can be challenging to find a good spot for a 18" Heater. -1 Star for the length.

I really like these Jaeger heaters. They work well and are dependable. Simple to use. I never have any problems with them. When I worked at a LFS, that is all we used.

I have used these heaters in the 200w for many years, but recently I upgraded to a new sump with baffles... And the heater won't fit anymore. Most heaters in the market arent this long. They're good but too long!!!

Great heater, agree with another reviewer that they are sometimes too long for their ratings, but otherwise excellent. Should have bought this heater first.

This heater does what it was designed to do. I have two of them currently running, one on a ~110 gallon reef, the other on my water mixing station. I have not had any issues with them and do not plan on replacing them with a different heater.

Since setting up my 28g nano, I have been fighting temp fluctuations all day every day. I bought a 100w VA brand when I bought the tank and it was never even close to accurate. Decided during the sales of Black Friday to get a 125w Eheim and it has been the best decision. After looking at the flat one from another manufacturer I saw at Palooza, I decided on this one instead. Reviews were pretty solid and I know they have been a solid brand over the years. Now, my temps might move about 0.5 degrees between day and night. I don't have to keep fans on the tank, adjust the temps, or anything. It just works and holds true temps. Word of advice: Don't Cheap Out On The Heater!!

The Jager heaters have been around for a long time and have consistently remained among the top recommended in the hobby. I am pleased to say that nothing has changed. They maintain a consistent temperature and the ability to calibrate ensures accuracy. Of course, they are even better if you drive them via a dedicated controller. They also have shatter-proof glass and dry-running protection where they will automatically shut down if they detect they are not in water. The only negative with these is the size. Please be sure to read the chart and measure out how much room you have. I took 1 star off simply for the size. If they could shave a few inches off of these, they'd be a perfect heater.

If you want a junk heater this is the one to buy. I bought two for a 300 gall Pacu tank, both failed within a month. I will never buy another Eheim heater. Says there fully submersible, both of mine had water inside the heater. DO NOT BUY.

I have a 150 watt on a pretty small tank and I've found that the temp fluctuates between 76.2 and 78.8 degrees regularly (monitored by an Apex system). 2.5 degrees is a pretty big swing for a reef tank, I actually have two of these and they both have the same issue. It may be that the tank is too small and the residual heat continues to heat the tank after the Apex turns it off but I see no reason for it to not turn on at 70 degrees where I have it set. The adjustable heater control ring is just about impossible to use too.

The heater is constructed out of high quality material.

Only heaters I've ever had. I replace them every couple of years since they are relatively inexpensive, but never had a failure.

I've been using these heaters for many years, I keep coming back to what has worked for me over and over again. Can't go wrong with these eheim heaters!

I have used one in the past in my fresh water tanks and needed a replacement for my FOWLR tank. Great product.

Eheim is used to be the gold standard in the past for glass heaters but the new one I just bought didn't work properly, it heats up for like 5 minutes and turns off, hopefully I am an edge case.

I bought 2 of these guys, and within a week of use, 1 had failed. Eheim sent me 2 replacements. The first one failed and actually burned out an outlet. The second one they sent me had the cable cut. I will never buy Eheim again. View my topic on this matter on reefcentral: http://reefcentral.com/forums/showthread.php?t=2578770

This is a great heater. Easy to use. Well built. Would by this one again.

I have this heater on a 55 gallon display with a 240 gallon sump (yeah I know...serious overkill). Originally I had a 265 gallon display but when the bottom fell out, the 55 was pressed into service. My tanks are in a converted garage that we euphemistically call the family room. It is very cold in there in the winter. This heater keeps the water warm nicely. My only concern is that it never seems to shut off. Would I recommend it? Time will tell.

the heater is not working good, from day one, it's always on. But the problem it's that I called Eheim customer service and I tried about 4 times and every times that you're supposed to get thru and talked to someone, they send you to a voice mail, and you leave a message but they do not have the decency to return your calls. Eheim it's not worth a penny

These heaters work amazingly well and the built-in controller is really pretty good at not bouncing on the threshold all day (which shortens the life of the unit). I have double insurance in place with these plugged into my Apex, but could not be happier with the high quality of these heaters.

Luckily this heater is able to be calibrated. After watching it closely for a few days, calibrating accordingly, it heats to the correct temperature and keeps it that way.

The Eheim heaters are the only ones I use nowadays, from freshwater and reef tanks to quarantine and mixing the bucket. I've never had a break or failure. One word of caution: make sure you check the size before you buy! I've found these tend to run a bit large for the wattage compared to other brands.

Bought a heater from a big box pet store to get my by while I waited for my Eheim heater to come in. The other heater I could never get to balance properly however the Eheim after one calibration is spot on and works like a charm. Thanks Eheim for making a quality product.

have this on my saltmix tank so temp is perfect to my display makes for fast and easy water change without having to wait for temp to equal works great

I bought 2 of these 100 watters for my sump. I've always used eheim products, but this time was different. My DP was at 79F when I put the heaters in, both set to 77 on their thermostats, and they both turned on (actively heating) when I plugged them in. An hour later, they were STILL on heating the water to around 85F. So, it seems like the thermostat in BOTH of them just doesn't work. I bought a finnex heater and synced it up to an apex controller, and will never look back.

This was a reasonably priced heater, purchased for my 180 gallon aquarium. It does heat well, however we do spend a lot of time watching and adjusting the heat. We do have it on a timer as well.

Quality heater at a reasonable price.

I have 250 w to my 120 g tank, work excllent, great temperature control

I run about 450w of total heat in my 120g sps system. I have two plugged into my apex and have had no issues so far with either. I have two more in the basement keeping my salt mix warm. Great trustworthy simple devices.

I have the 300 watt heater for my 120 gallon reef tank. I find it to be accurate and reliable. Simple to use and a good product. Costs about $20 less here than at my LFS.

Use 50w in some 10g tanks I use for saltwater nursery tanks and quarantine. Holds temp steady well and have not had any issues so far. Have some other Jager heaters that are going on 10yrs now and still fine.

Overall a superb heater, however it is pretty long. and as I do not have a sump I had to hide it behind my reef saver rock. Not a daunting task but im hoping the length with help with longevity

Nice heater. Does the job. It is hard to get regulated, though. The dial isn't that easy to turn. Had to set up my chiller because when you set the temperature high enough to do the job...it tends to get a few degrees warmer than I want it to be. Well constructed, tho!

Have been using the jagar heaters for years and have never had a, problem with them I would recommend them to others.