boxtech Aquarium Heater 300W, Submersible Fish Tank Thermostat

I have several of these. They work great. As they say they don’t explode if you accidentally start doing a water change and forget to unplug your heater… oops. I like how sleek they look in my tank and they take up half as much room as other heaters that barely work

So I started out like most in that I needed to replace my existing heater for my 10 gln tank. But no matter which heater I looked up, even the more expensive ones, the reviews always seems to have around a 3rd of them with horror stories of killing their fish.So then I found this heater.. had very few reviews, but of the ones it did, none of them were about killing fish. Most of them were about the red light coming on and then right back off (more on that later).So first things first, what I really liked about this heater is it turned out to be really small. So small in fact that initially I didn't think there was anyway it would heat my tank. But it is because the Themo is outside of the heating element (and outside the tank). So it makes for a really small device actually inside your tank which allows you to put it almost anywhere (good thing too... more on that below).What I do NOT like (and why I only gave it 4 stars). The Wire length between the heating element and the Thermo housing is plenty long.. almost too long. The problem is the wire length between the Thermo housing and the wall plug is short.. like only a few inches. Which means, that depending on your power setup, you may find that the Thermo housing has to sit down the wall behind some furniture or some other hard to see\reach place. The good news is that once you have it dialed in, you really don't need to have access. However I personally like to be able to easily see it so that I can tell when the heater is actually on or not (aka the red light).*** WATER FLOW ***Which brings me to the main point. Like most probably, my original heater was rather large and so I had it vertical in the back corner of my tank. Also, because the Thermo was built into that one, by having it vertical I could more easily get to the adjustment. So naturally I placed this new heater in that same spot.However, in doing so, it did not take long to see the same issue that some others were having. I have a Digital Thermostat w/ alarm on my tank and the new heater did not appear to be raising the temp and the red light would come on and then go off within moments. I reach into the tank and felt the heater and it was hot and that is when my own light bulb went on.This little heater works so well, that it was quickly heating the water around itself up to temp and shutting off. The problem is water flow. So I moved the heater close to my Filter intake and actually placed it more horizontal just above the gravel.. and presto! The red light would come on and stay on and the temp would begin to rise.I spent the next 2 hours slowing increasing the dial each time the red light turned off until my Thermo read 77.5 degrees. It has been 3-4 days since then and my Temp has stays right at that same point +- 0.1 degree.Time will tell of course as for the durability. But I just wanted to pass along that this heater requires some sort of decent water flow. If you have an HOB filter, placing it next to the intake like I did should be ideal. if you have a Power Head, then putting in front of the outlet might work better.Side note... as for the Temp "dial".. well it is in Celsius and I never even really looked at it because I started low and went off my Tanks Thermostat. But in the end, when it was all said and done, I ended up with the dial pretty darn close to the 25 mark on the dial which would be 77 F.** Update **So it has been a couple of weeks now and I just wanted to report back. Now assuming that my digital thermo isn't the culprit, my heating temp does vary a bit more than originally noted... but wait for it... I now have seen temps flux between 77.2 and 77.8 :)So my original claim of +- 0.1 degree has now been updated to +- 0.6 degree .... I'll still take those odds any day of the week!** Update **So I had nothing but good things to say about this item...until now. I had purchased this at the end of March (2019) and it is now the end of Dec (2019) and it stopped working. I almost bought it again until I realized it has only been 8 months... :(

I am using the 50w in a 2.5 gallon aquarium. Very accurate and does not fluctuate. I really like the outside temperature control. 2 thumbs up! I am buying another for another small tank I set up.

I found the texture helps when applying to permanent locations. The fish will also enjoy the warm glow it brings to inspirational tank life.

I did not realize, or maybe it wasn't explicitly called out, that this thermometer displays Celsius only. Minor irritation, but to ensure I didn't actually fry my fish, and b/c I'm not up to speed on my Celsius-to-Fahrenheit conversion, I Googled that shiz. Anywho, just know it's easy enough to do that if you need to.This heater is super compact, which I love. I have it in a 9 gallon Fluval Flex, which has built-in compartments in the back and so I needed a smaller heater to ensure it'd fit well in next to the pump, which shares the same compartment.It's in there, working great, and there's room to spare. I've been closely monitoring the temp of the water with a separate thermometer and so far it's holding steady at the desired 78*.The only thing I really am not a fan of, is that the cord is thick and round, instead of a flat cord. This makes it a little bulk in sitting nicely in the pre-cut part of my aquarium lid, but it's also not something I even thought about either, until after it arrived and I installed it. Also minor inconvenience, but just know if you have an aquarium kit w/a pre-cut area for cords to come from a lid, that is something you'd want to take into consideration.All in all, it's working great and doing its job.

Product arrived in good condition as expected. Heater was placed in a 10 gallon tank under moving current and brought the temperature up to 70 degrees F from 60 in about 2 hours (dial setting at 75). Note, the thermometer is placed at the opposite end of the tank. Temperature is easily set with the attached dial, and although no aquarium heater is aesthetically pleasing (IMO) - this one isn’t too bulky or flat out ugly like the others. The biggest limitation I have noticed thus far is that the power chord is way too short, so an extension chord is a must for certain setups. Furthermore, the temperature control dial is only about 6 inches from the power chord connector (expect to bend down to change the temperature if you have a low to the ground outlet).

I have had this in a 5 gal betta tank for about a month now. So far, it is keeping my tank at 79 consistently, but it took a bit of calibrating to get there. Like any heater, don't rely on the dial to accurately match what temperature you want. Get an actual thermometer for that and make checking the temp part of your daily routine.I'm giving this 4 stars because the cord from the dial to the plug is ridiculously short. Thankfully I don't have to adjust it often, but I would prefer a longer one.This heater is inexpensive and so far, reliable. If I get a couple years out of it, I'll consider it a successful purchase.