[Amphibious]

Put the heater in the tank or sump where ever you are going to keep it. When you plug it in, if the heater comes on a little light will come on also indicating the heater is going to heat the water. Turn the nob on top of the heater counter clockwise until the light goes out. check it in five minutes. If the light is back on, turn it down again until the light goes out again. Check your temperature with an accurate thermometer. Keep doing this until your temperature does not rise due to the heater coming on. Realize that during the day your temp may go up due to living in FL. (I'm down here too, Ft Pierce) Keep checking your temperature and the light in the heater. You should get it balanced out in one day, but check it often. As mentioned above, cheap heaters can go haywire. As soon as possible get a better heater. I bought a titanium heater with remote control for under $20 so maybe you should consider getting something like that.