heater observations

My heater is about 2 months old & is looking strange at the bottom. I'm uploading a pic. Does anyone know what this is about & if I need a new one already?? Ughhh

Hey guys! Brand new to the page, my betta fish got a new heater and its been at a steady 84 degrees Fahrenheit and that's a little warm for my comfort so my questions are 1. do you think this heat is okay? 2. If not, is it okay for me to turn it off for a couple of hours and then turn it back on?

Just upgraded from a 100l TO 250l tank. The tank is in a cool room.   My previous 75W heater in the 100L tank used to stay on for about 20 continuous minutes in an hour. It was positioned horizontally at the bottom in the middle of the tank.   However the new 200W heater in my 250L tank is...