Why isn't my heater doing it's job?

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Pazzoman

Piranha
MFK Member
Apr 5, 2009
3,005
50
81
New York
My rena smart heater which this model that I have is rated for 90 gallon tanks.

My heater keeps flashing on and off. The temp of the tank is 71!!!!!!!!!!!I don't get his, but then it goes back to normal the next day.

I have a 72 gallon tank.
 
what temperature is your house at night? A heater can only compensate by so much.
 
How many watts is the heater? I'd suggest 5-8 per gallon. And like Heath posted, if you have a cool house, the heater will need to work harder.

There are other factors as well. If the water right by the heater is getting to the temp, it will shut off...so you need good circulation. Could be a heater failure as well. I've never been a fan of glass tube style heating units...they fail a lot.
 
I've been using those heaters for a few years now.

For a 72 gallon I would not use anything less then a 300 watt.

Also, these heats need to be vertical in your tank and work best when there is flow through them, such as the intake for your filter.
 
Cliff519;4592758; said:
I've been using those heaters for a few years now.

For a 72 gallon I would not use anything less then a 300 watt.

Also, these heats need to be vertical in your tank and work best when there is flow through them, such as the intake for your filter.

+1...maybe its a funky heater. Continue to adjust it up until you reach the desired tank temperature.

The light going on and off around 71 to me would seem to be an indication that it is thinking that is the temperature you want.
 
Well i have it horizontal for the past few weeks....possible answer is vertical. I think it is the 300 watt heater since it's for 90 gallon tanks. Also it is not glass heater.....I stopped using them because my fish would get close and burn themselves. This is a plastic heater.
 
The light only comes on when its doing work. If the light is going on and off near 71, and you have it set towards 78 then you know that it is mis calibrated.

Otherwise it is shorting out. Either way you may want to replace it.
 
sounds like a faulty heater I would return it and get a new one better safe then sorry you could have cracked it or it could have cracked in transit.
 
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