I find large wattage heaters (like 300s) are problematic (all heaters crap out, I've had them all over 50-60 years of fish keeping Jagers, Eheiims , Hydors, titaniums) and for me, at least 50% of the time the thermostats crap out in the "On"' position, and cook the tank.
So I prefer and always use 2 or 3 smaller wattage heaters per tank, in that way, if one stays in the "On" position, the thermostats on the others turn off, and the smaller wattage ones can't cook a tank in the 125 gallon range.
And for many tropical fish, room temp is just fine (maybe better). When I lived in Wisconsin I unplugged most if mine, May thru September.