Works great. I have it for my 2.5 gallon pico reef and it has never let the salinity move. It is very sensitive which is great and I have never had a problem with it. The only thing I don't understand is why when I plug it in it turns the pump on for a couple of seconds. It is kind of annoying and I don't get the reason for it, but it isn't hard to get around,just unplug the pump. It comes with plenty of sensors and hanging kits to get any job done. I definitely recommend this ATO to anyone, it isn't very expensive ($70) compared to the other ATOs out there, and it does its job well!