On Off On Off On Off On Off

[dazbud]

Just upgraded from a 100l TO 250l tank. The tank is in a cool room.
 
My previous 75W heater in the 100L tank used to stay on for about 20 continuous minutes in an hour. It was positioned horizontally at the bottom in the middle of the tank.
 
However the new 200W heater in my 250L tank is switching on and off appox every 1-2 minutes. Its an All Pond Solutions heater and is positioned vertically (as pictured on the box). I have positioned it at the bottom corner of the tank next to the intake of the external hood trickle filter. after being on 24 hours the temp has reached 25. I had set the guage to 25.5, so it looks like its maintaining the temp OK.
 
However, is this normal to switch on and off so often?

 

[DrRob]

I find they do this if there isn't enough flow over them, and they're often better at a slight angle so that the rising warm water doesn't turn off the thermostat.

 

[techen]

my heater comes on like once every 4 hours and I stay in scotland xD

 

[tomtomtom1230]

Regardless of what the box says, put it on an angle and see if it makes a difference

 

[dazbud]

I've tried horizonal, diagonal and vertical. The same switching pattern.
 
Using a stop watch, I've calulated that its on for an average of 40% of time, which is what my smaller tank was, and the overall water temperature has been a static 25C. So I'm feeling more confident that its working correctly. Just not used to a heater cycling on and off so rapidly.
 
I had read some other articles since posting this question and dicovered that some newer heaters cycle quickly so as not to over heat. Don't know if this is true.