Hygger Fast Heating PTC Aquarium Heater with LED Digital Temp Controller 500W Submersible Fish Heater for 60-120 Gallon Freshwater Tank

I wanted a compact submersible heater to keep the water warm in a little 4-gallon rock fountain we have on our front porch. Our winters aren't awful where I live, but the temperatures do get down into the 20s or even teen occasionally. We have a few goldfish in the fountain and wanted to let them just "winter over" in there. This heater is small and flat, and has been able to keep the water at 68 reliably. I would actually prefer to keep it a little cooler for goldfish, but 68 is the lowest setting and the fish tolerate it just fine. It warms the water without the heater being a "hot spot". The controls are intuitive and easy to use. One word of caution. It is important that this heater has water flow on all sides. I placed it flat on the bottom of the fountain floor and it worked for a day or two and then shut off with the error code that it was "out of the water". I unplugged it, removed it from the water for a few minutes, put it back in, and it restarted and worked fine, only to flag the same error again the next day. I finally figured out that having it flat on the bottom throws off its temperature sensing and it thinks it is overheating. Just propping it a 1/2" off the bottom on a small rock was enough to stop the problem and it worked beautifully ever since. I would highly recommend it for use in an indoor aquarium tank as well, as it is very accurate (compared with two other thermometers) and it doesn't vary by more than 0.1 degree over a whole day from warm afternoons in the 50s outdoors to very cold nights in the 20s.

I do not write a lot of reviews unless I am really impressed (or disappointed) so here goes - After exhaustive research and finally deciding on which heater to buy, I am completely convinced this is the ONE AND ONLY heater anyone will ever need. I have placed two of these to heat my 280g mixed reef tank. With over $10k in fish and coral in my display, I am not going to cheap out on the heater! And this is the ultimate best you can get. First off, the heating element is conductive ceramic - The heating element cannot break or warp or crack or anything. There's no coils of wires and insulation and all that. The heater body IS the heater; there's nothing to break. The heater temperature is proportional to current temp and temperature setting difference. If the setting is a lot higher, it cranks out 500w, Which is almost enough to create localized boiling (keep plants away). But, as the temperature difference gets smaller, it ramps down the power proportionally. So you get both a rapid heating for things like water changes and low power consumption for steady-state temperature. Next, it is easy to program. Just one button. A huge lighted LCD displays show you the setting and the current power mode. And, also a great feature, it remembers your settings. So, if there is a power failure, or like me, if hooked up to a separate temperature controller, it keeps your settings in memory for when power returns. The only thing I cannot comment on at this point is life-span. I am guessing that, with the ceramic design, this heater will last many years (if not decades). This one definitely is worth my time to rate it and to write this recommendation. I am very happy with it.

Absolute garbage. I bought two of these for my 125 gallon aquarium. One for regular use and one set a few degrees lower as a backup. Within a month or two, both heaters were displaying error codes. Contacted the seller to let them know both were having errors. I was told to unplug them and leave them out of water for 24 hours. They are supposed to be submersible, so what good would that do? Neither worked after the 24 hours, so the seller said they would send replacements. Only one was sent, and that one started to show error codes within two weeks. The temperature seemed OK, so I left it plugged in. Today I went to feed the fish and noticed a lot of heat coming off the water. Checked my thermometer, and the temperature was 93°F! Almost cooked my entire tank. Not worth it, especially considering the price. Worst purchase I have ever made on Amazon.

I originally ordered 2 of these heaters BEFORE these new titanium models came out. They were both working great, but had 1 fail on me one day. Still within the return window, I notified the company & they immediately sent out a replacement with the new titanium model. You can tell it's a heavier, better made product. These latest ones also only have 1 button to fool with=SIMPLE. I've measured the accuracy with a digital thermometer & so far, the heater is always within .5 degrees. I'm VERY pleased with both the product & the company so far! I have 90 gal & 65 gal aquariums & it's so awesome to be able to regulate temperature from the OUTSIDE of the tank & so easy to see the reading at a quick glance! This product makes using the old glass heaters a thing of the past for me-easier to use, more discreet inside aquariums & safer! THANK YOU HYGGER!!!

these little buggers are amazing, I have it in my sump in a section that contains maybe 5 gallons, 100 gallons in circulation total. and it works great! I had recited some fish that had ich and raised the temp to 89 for 4 days and it keeps pace. easy to control, set, read. ill never buy a different kind. also it reduces the risk of electrical shock with smart tech, which I've experienced from the hard plastic card traditional models.