Oh no...water temp fluctuations

[chasely]

I checked my tank this morning and my temp was down about 6-7 degrees below what it normally is. I've turned up my heater to 85...and the temp hasn't hanged at all.

I have no idea what is going on...and I'm worried that my heater may be broken. Anyone else experience this problem. I did about a 10 percent water change yesterday and adjusted my light hours down about 4 hours, but none of that should have any effect on the water temp if my heater is working...correct?

 

[OCCFan023]

whats the size of the tank/heater wattage. and how long has the tank been running

 

[fishmaster]

i had this problem with my heater. you have to keep track of the temperature and keep adjusting the knob until it cooperates with the right temperature

 

[Lotus]

Does the heater have an indicator light? If so, is it coming on? Did you unplug the heater before the water change?