If your water capacity is within the range for a 100 watt heater (up to 30 gallons), then, yes, you have a defective heater.
answered 1 year, 8 months ago
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All depends on what you are using to determine the true water temp. To be within 3 degrees is pretty good for most Petco type merchandise.
answered 2 years, 11 months ago
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from what i know about shopping for a heater is that the actual air temp and how much water you are trying to heat up will make that temp vary. the preset to 78 would ensure that it does not go above that temp but it would have to be optimal conditions to stay at 78 consistently. hope my two cents helps.
answered 3 years ago
1out of 1found this answer helpful.