Review on Boxtech Submersible Aquarium Heater 100W by Colleen Vazquez

So, like most people, I started by replacing the existing heater for my 10 liter tank had to. But no matter what heater I'm looking for, even the most expensive ones, there are always about 3 of them in the reviews with horror stories about killing their fish. And that's how I found this heater. There were very few reviews, but none were about killing fish. Most of them involved the red light coming on and then going off (more on that later). So what I really liked about this heater is that it turned out to be very small. So small, in fact, that initially I didn't think it would even heat up my tank. But that's because Themo is outside of the heating element (and outside of the tank). As such, it's a really small device in your tank that allows you to place it just about anywhere (also fine. More on that below). What I do NOT like (and why I only gave 4 stars). The length of wire between the heating element and the thermos is large enough. almost too long. The problem is that the length of the cable between the thermocouple and the connector is short. like just a few inches. This means that depending on your power supply you may find that the thermal case needs to sit on the wall behind some furniture or some other hard to reach spot. The good news is that once you dial the number, you no longer need access. However, I personally like being able to see easily so I can tell when the heater is actually on or not (aka the red light). ***FLOW OF WATER*** That brings me to the point. My original heater was probably quite large, so I placed it vertically in the back corner of the tank. Since the thermostat was built in, the vertical placement made it easier for me to set it. So of course I placed this new heater in the same place. However, it didn't take long to start seeing the same problem as some others. I have a digital thermostat with alarm on my tank and the new heater didn't seem to raise the temperature and the red light came on then went off after a few seconds. I reach into the tank and grope for the heater and it was hot and that's when my own light came on. This little heater works so well that it quickly heats up the water around it and shuts it off. The problem is the water consumption. So I moved the heater closer to my filter inlet and actually positioned it more horizontally right above the gravel. and voila! The red light came on and stayed on as the temperature started to rise. I spent the next 2 hours slowly increasing the dial each time the red light went out until my thermometer read 77.5 degrees. Since then, 3-4 days have passed and my temperature remains at the same level + - 0.1 degrees. As for durability, of course, time will tell. But I just wanted to convey that this heater needs a decent amount of water. If you have a HOB filter then placing it next to the intake like I did should be ideal. If you have a power head, you better put it in front of the socket. Note. as for the "dial" temp. Well it's in Celsius and I didn't even look at it because I started low and the tanks thermostat was turned off. But in the end, when all was said and done, I got a dial pretty darn close to the 25 on the dial, which would mean 77 F. **Update** So a few weeks went by and I just wanted to get back to you. Well, assuming my digital thermostat isn't to blame, my heater temp is fluctuating a little more than what was initially shown. but wait. I've now seen a transient flow between 77.2 and 77.8 :) So my original statement of +-0.1 degrees has now been updated to +-0.6 degrees. I will take these chances any day of the week! **Update** So I have nothing but good things to say about this item. so far. I bought it at the end of March (2019), now it's at the end of December (2019) and it doesn't work anymore. I almost bought it again until I realized it was only 8 months ago. :(