Hello! I bought a Eheim jager 25W heater for my fish on Sunday and it just arrived today. The only thing is a small white plastic ring used to stabilize the thermometer at the bottom was broken when I opened the package. It already has suction cups to hold it up. Do I need the white plastic ring? If so I will have to send it back. :/ Here's a picture:
Also, the instructions for the heater says to just stick it in there and make sure it doesnt over heat/under heat. This wont hurt my fish, will it? I read somewhere a great variation in temperature can kill a betta. The temperature should adjust slowly enough with the heater that it wont hurt my fish?