I also have the inkbird set to celsius and that helps but not a ton. I will say my cobalt neotherms in my 75 stayed between 77.9 - 78.1 and nothing else! might wnd up going with 2 300 watt neotherms.i run a 600 watt on an inkbird in a 300 gallon tank and I still see a 1* swing all throughout the day