hygger Small Submersible Aquarium Heater 100W Mini Betta Fish Tank Heater with Thermostat for 10-20 Gallon Saltwater Freshwater

CLIFF NOTE VERSION: Both heater work very well. The Nicrew is smaller, less obtrusive, but not adjustable. The Hygger is a tad larger, is adjustable, and has a large red LED readout of the tank temperature.LONG VERSION: I have purchased mini-heaters in the past and they either didn't heat or fried the water. I long ago learned to do the bucket test. I purchased the Nicrew Mini (15 watt) and the Hygger (15 watt). The Nicrew is smaller with a preset stated as 76 degrees F. The Hygger is adjustable with a large LED readout. It is super easy to set. There’s a rheostat type adjuster that’s on the cord. The readout is on the heater. That makes it easy to bump the heat up or down without sticking your hand in the water. The downside is that the light on the heater is noticeable in the tank. You’ll want to hide it with plants or décor if you’re going for a natural look.Both were placed in a 3 gallon bucket of 70 degree water for one hour before plugging in. This is a manufacturer suggestion, and, IMHO, failing to do this is bad for the heater. The room was 70 degrees. I plugged them in and set the Hygger. An hour later both buckets of water were at 74-75. That temp held for 24 hours, even though the room temp dropped to 65 at night. I'm now using the Nicrew 15 watt in a 2.5 gallon tank and I’ve very happy with it. The Nicrew holds rock steady at 74. I'm keeping both heaters. I'll use the Hygger in the winter when the room temp is much colder and I may need to use the adjustable feature to compensate for the room/tank temps. I used a scientific thermometer for my readings. Big thumbs up for both heaters. I suggest you do the bucket test as heaters can vary.

Used these heaters in my 5 gallon shrimp tanks and they work wellJust place in tank, wait 30 minutes and plug them in. It’s that simple.

I now have 2 of these heaters for a 2.5 and a 3.0 gal aquarium, respectively. After 8 days of service I am happy with their performance.The problem was the initial temperature set up. The instructions were poorly translated from the original Chinese. After getting an error message on the thermostat that the heating element was dead, and then not being able to contact the manufacturer, I decided to try a different plan. My approach worked!When the 2nd heater arrived I used my method and had immediate success.

The availability of small 25-watt heaters for 5-gallon aquariums is extremely limited. This one seemed like a decent quality heater for a fair price. After 14 months of use, I noticed the display was flashing between 'EL' and the water temperature. The heater was still functional, the red heater light properly cycled on and off as the heater cycled, but I did not wish to risk electrocuting or cooking my betta because I ignored an obvious warning light. It seems that these days, for the price we pay for things and the service that we receive from them, it is more like we are renting these items than buying them. There is a planned, designed, and limited service life, and the item is priced by its approximate value per month. Ce la vie.I still expected more than 14 months of life from this heater when I bought it though.***UPDATE***As stated previously, quality 25W aquarium heaters are hard to find. I reordered this one because it seemed the best choice of available options. Upon opening the new one and reading the instructions (GASP!), I read about the EL end-of-life code. It is set for 10,000 hours. Got on the internet and asked how many hours in 14 months, and guess what? Almost exactly 10,000 hours! So, my only real beef is that this is not made clear in the product description. If I know that I will only get 14 months of service out of this device, then I can decide if it is worth the price. IMHO, it is. And after thinking about it, I appreciate that the device tells me to replace it BEFORE it cooks all my fish, which is what my last aquarium heater did, without any warning. Sure, I got several years of service out of that one, but at what cost? At least this one lets me know when it is a good idea to replace it. Upon further consideration, I am changing my review from 2 stars to 4. I would have given 5 stars if it had been made clear up front that the service life of this heater is 14 months. As long as the price remains fair, around $18 or $19 (or less!), I think it is worth that price and would have earned 5 stars if the product description made it clear that it would only last for 14 months.

This heater is perfect for my 20-gallon tank. Its small enough that it doesn't take up too much space, and still has enough power to keep the tank at 78 degrees. This of course changes depending on the size or your tank, whether or not you have a lid, and the ambient temperature in your house. In my case, its perfect. Easy single button operation, clear temperature display, and good safeties in place in case it overheats. So far no issues.

I was initially impressed with the value versus quality. The temperature was easy to set, easy to read and accurate. They were great for a little over a year and then one by one they stop working. The metal and coils inside start rusting and the heater stops working. Between 2022-2023 I bought four of these. I only have one left still working. Fortunately I have multiple heaters in my tanks so I avoided disaster. If you're looking for a cheap temporary solution then this heater is great...not so great long term.

This heater maintains the temperature well for a very good price. I like how small it is overall. This is my third heater of this design and I will continue to purchase more as needed.

Like the design of the heater, easy to set the desired temperature and read the current temperature. Don’t like that it stopped heating the water after two months but the temperature display stayed on as though it was working. My water temperature was set to 80 and it dropped to 73 over a period of a few days so I removed it from the tank and replaced it with a more reliable one from another company. I lost several fish when the temp dropped so I’m really not happy with this product and would not recommend it to anyone. Sadly I’m past the return date by a month or I would be requesting a refund.

I had a different brand heater and it was always a few degrees hotter than what I set it to (around 75)I put this heater in a tank that's a couple gallons bigger than what it's rated for but since the temperature is only set to around 75 it is perfectly stable and has no problems. It's nice and small

Muy buen calentador, muy preciso, muy fácil de manejar y excelente calidad

I take my review back I think this heater is actually doing good so far just had to change the temperature again :)

I finally have an aquarium heater that heats up the tank and keeps the heat in it. Digital is the only way to go.

Nice smaller size for nano tank, just wish cable was more flexible. I’ve had more powerful thermos with cables easier to tuck behind plants.That being said, not unhappy with purchase. Easy to adjust temp and lights a bit bright, but it’s nice to see running temp.