Cobalt Aquatics Flat Neo-Therm Heater with Adjustable Thermostat (Fully-Submersible, Shatterproof Design) from 25W to 300W

I've purchased a good number of aquarium heaters over the years and they were all variations of the same function and design, and has virtually remained unchanged for over five decades--a long tube, glass or plastic housing, with heating elements, which were then connected to some sort of thermostat circuitry. My last one, an Aqueon unit, malfunctioned and almost wiped out my whole tank's population because it overheated the aquarium and did not have a safety defeat mechanism. I lost 3 neon tetras, and two nerite snails in this incident and swore, (not verbally), that I would never use tube-type heaters again.Enter the Neo-Therm heater. I was struck by the new, sleek look; very modern and high tech. It wasn't a tube form factor, but was flat, which seems to provide more surface area to be in contact with the water.The LED readout is a great way to check on the water's temperature at a glance, and tells you whether you're up or down in the desired temperature you preset for the unit. One solid LED means your set temp and tank temp are the same. A flashing light before or after your set temp means it is higher or lower. To adjust the temp, you press a button located at the top of the heater, which is a bit difficult to push because it is small, and a bit slippery. But no biggie.Unlike tube type heaters, the numbers on the LED dial actually mean something, whereas, tube style heater numbers don't even correlate to the real temperatures at all, in most cases. All they do is act as a reference point for setting the temperature and this can be extremely inaccurate.I purchased the Neo-Therm and had it up and running in no time at all, not counting the recommended 15-minutes (or more) for the heater to calibrate itself when you first put it into your tank. After this I plugged it in and watched the LED dial display the water temperature. It already has a factory default temperature setting for 78 degrees F., so this makes it very easy to set up.This heater is solid-state, and according to the manufacturer, in the unlikely event that the unit fails, it will simply turn off, and not continue to heat the water. This feature alone makes the purchase worthwhile for me. The accuracy of the Neo-Therm is spot on as I verified the +/- 0.5 Fahrenheit degree accuracy of the unit with a digital thermometer. I was very impressed.The Neo-Therm is sturdy and the outer casing is made from shatter resistant plastic and should hold up for a very long time to bumps and bruises.There were a few issues though. The first unit I ordered was inaccurate to about 1-2 degrees and persisted in this false reading over two week's time. I return this unit, received a new one via Amazon's outstanding customer service, and the replacement unit is flawless.The second one is subjective and doesn't affect the Neo-Therm's functionality, but may be an issue for some. The temperature display numbers, which circle the LED readout from 66 to 96 degrees, are set in multiples of two, or in other words, all even numbers. So if your tank temperature is really 79 degrees F., the display will still show it as either 78 or 80, depending if it decides to round off up or down. So for OCD types, this may be a deal breaker.I've seen the Neo-Therm flash two numbers simultaneously, and perhaps this is the way it tries to show you the in-between numbers, but I only saw this happen once, and it happened with the unit that I returned, so it was probably a fluke. Maybe in the next software update, this could actually be a feature to show the "tweener" numbers.But outside of these two issues, I am very happy with the purchase. Yes, it is more expensive than other aquarium heaters, but if you total the cost of all the heaters you've bought over the years, and have failed or become inaccurate, this makes the Neo-Therm a bargain when you compare the price differentials and performance.

I was looking for a heater for my new 2.6 gallon tank but every heater I found either had horrible reviews or weren't adjustable and people said with such a small tank it would cook my fish. When I stumbled upon this heater I was impressed with all of the glowing reviews and everyone saying it not only maintains the water temperature by it actually heats the water. A lot of reviews for other heaters said the heaters only maintained temperature, it didn't raise the temperature. I couldn't ignore all of these reviews, obviously this heater does something right so I ordered one.I just got this heater today and so far it seems to be working perfectly, a little too perfectly as it seems to be warming the water 2 degrees higher than what I set it at (this is confirmed not only with a separate thermometer but also by the heater itself) but this is no big deal, I just set the heater 2 degrees colder than I want.The heater is very slim and not too long, it fits perfectly even in a fairly small tank like mine. I didn't realize when I ordered it that it also acts as a thermometer but the way it's situated in my tank makes it really cumbersome to use it for that purpose (which is no fault of the product itself) so I still rely on a standalone thermometer for that purpose. Both the standalone thermometer and this heater show the same temperature so I'd say this is fairly accurate as well.The only complaint I have is something another reviewer mentioned; the suction cups don't work at all. I push the heater where the suction cups are against the side of the tank and they'll stick but then I'll check the heater a few minutes later and the suction cups have failed. I have no idea if the suction cups just aren't very good or if they're not meant to work on the type of surface I am sticking them to, it's like frosted glass or acrylic, not sure on that. However this isn't a big deal for me personally because the heater itself is situated in a small chamber so it doesn't really move much anyways but if it wasn't I would be worried that the heater might float on its side towards the top of the tank which the instructions say is bad.Overall I am very satisfied with the product and would highly recommend it. Sure it's a bit pricey but then again you get what you pay for. Instead of buying a sub par 10 dollar heater that won't work very well put another 20 dollars towards your purchase and buy this high quality heater.