Letsgometsreyes said:they dont but there very accurate i have both at 79 and my temp gauge says 79.5![]()
It's why I went with the Marineland Neptune line, I like to know when the heater is on since I tend to ignore the thermometer. I once accidentally turned the temperature up after cleaning some algae off the top of the heater. I noticed that the light seemed to have been on a long time, and sure enough, I'd upped the temperature to like 82 (from 76). If it weren't for the light, I wouldn't have known unless the fish cooked or the water felt too warm at next water change. That's just me though - I'm sure some people check their thermometer a couple times a day.