Rated 4.1 out of 5 by 10
Rated 2 out of 5 by MissKeys Should NOT be rated for 10 gallons!
Supposedly this single 15W heater can heat a 10 gallon tank and . The one I purchased doesn't get my (tetra/danio/trapdoor snail) tank above 76F on it's best day but even if it does get to 76 it never holds the temp there. It fluctuates all day, every day and drops as low as 72.
Temp fluctuation isn't healthy for the fish so I've purchased a replacement heater from a different pet store & by a different company that is also a 15W, auto thermostat heater rated for a 5 - 10 gallon tank and it had no trouble raising the temp (tank was 73F when I pulled this heater and put in the new one) to 78F and it also has no trouble keeping the tank at a steady 78F while sitting in the exact same place (by the filter outflow for good, constant water current/flow) in the tank as this old one. On top of actually doing it's job, the new heater was cheaper than this one!
Short but sweet: My 15W Grreat Choice Mini Aquarium Heater is now at the dump. I wouldn't recommend this heater for a 10 gallon tank. It probably can handle a 5 or 7 gallon tank but not a 10 gallon (20 inches x 10 inches).
October 6, 2015
Rated 3 out of 5 by Carolinagirl1028 Decent heater for the price
I purchased this heater for my son's 5 gallon tank. It is easy to set up and works okay but I really do wish it was adjustable. There have been a couple of times, esp. on warm days where this heater had caused the water to be too warm so I find I have to constantly keep a check on the temperature in the tank to see if I should unplug it or not. I will likely upgrade soon to an adjustable heater, but this has been good to have.
August 26, 2015
Rated 3 out of 5 by Kdtk Very tempermental.
If it doesn't work for you at first, try plugging it in and unplugging it every one in a while. I did this for about a week before it worked properly, but even then it only got my ten gallon to 76ish Fahrenheit. For about a month it was ok, but now it's not working at all.
August 4, 2015
Rated 5 out of 5 by potatodog Gets the job done
Its slim light weight and doesnt look horrible in tank. Holds the temp and that's all I need it for. Using the 10 gal compatible heater.
July 3, 2015