Originally Posted by mea2112
The thing that really frustrates me is neither of the two new heaters stays on for any length of time even though the water temperature is at 76 degrees and the heaters have been set to 80-82 degrees. They should stay on (pilot light lit) until the temperature reaches 80 degrees or so but they donít. The pilot lights stay on for a minute or so and then shut off. Very strange!
I tried one of the new Marineland Stealth Pro heaters (the old ones don't have any pilot lights at all) and the thing worked for a couple days and then died on me. Seems like all these new Visitherms have a quality issue since they've been "improved". So it wouldn't surprise me if that one you have is junk.
However, having the other heater do the same thing kind of makes me think it isn't a quality issue. That'd be pretty coincidental.
Do you have good flow around the heaters? If not, it could be that the water in the local area around the heater is heating up, but not spreading out into the aquarium water fast enough. Your heater then senses the locally higher water temperature and turns off. Then the warm water migrates away from the heater and the heater turns on again.
Like BigJim mentioned, I'd turn up the heater and ignore the temperature markings on the heater dial - they are *never* correct. Just set the heater based on your thermometers.