# Hydor ETH clicking



## SirKappa (Apr 19, 2010)

I just installed a Hydor External Thermal Heater (in line heater). Late at night and now that the house has settled down and I am on the computer I can hear the Hydor heater clicking on and off every couple of minutes. It is very loud for a click and it is very annoying.

Is it common for it to be turning on and off at an average of every 1-2 minutes?


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## SirKappa (Apr 19, 2010)

Actually I timed it yesterday after posting this. It is happening every 45-60 seconds. Is this normal for it to cycle on/off this frequently?


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## teacherthomas (Jul 14, 2006)

I have one and yes the clicking on and off sound is normal, however that frequency is abnormal.

Possible causes:
1) you have a very larger tank with an unstable temperature
2) You have a flow rate to the heater that is not proper (too fast or too slow)
3)you have the heater laying horizontal not vertical.


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## SirKappa (Apr 19, 2010)

The tank is 55 which has about 45 gallons of water(the heater is rated for up to 53g). The flow rate of the filter it is attached to is 145 gallons per hour from an Eheim 2234. The heater is hanging vertically.

I don't see how any of these can be the root cause of the problem.


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## Piranha_Owns (Jan 13, 2009)

mine clicks too i have a 300w on my 90 aga


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## SirKappa (Apr 19, 2010)

I know they all click but does yours click every 45-60 seconds?

I just timed it agian and now it is happening every 30-40 seconds.


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## Seattle_Aquarist (Mar 7, 2008)

Hi SirKappa,

When I size a heater I get 5 watts per gallon for each 9 degrees F (5 degrees C) above the average room temperature I wish to maintain. For example for a 50 gallon tank that I wanted to keep at 77 degrees F in a room where the average temperature is 68 degree I would use 5*50 = 250 watts. If the room is cool, like a basement, or if I turn my furnace down low at night, I go higher.

That may not be your problem however, it sounds more like it may be related to the flow through the heater. If the flow is slow, the heater will cycle quickly. The heater turns on, rapidly heats the small amount of water in the heater casing, and turns off. Once the warm water leaves the casing and cooler water enters, the heater cycles back on. Keep in mind that any "in-line" accessory will reduce the flow of our filters. BTW, if it has been a while since you cleaned your filter/ strainer you could try cleaning the filter which may increase your flow and reduce the amount of cycling the heater is doing.


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## SirKappa (Apr 19, 2010)

Hi Seattle aquarist. The room temperature is only 6 degrees F less then the desired tank temperature. The filter has not been cleaned for 8 days. I normally do it every second week. I will try this out and see how it goes. Thanks for the tip. 

On a side note I emailed Hydor and they didn't answer my question about the frequency of it cycling on and off, instead they suggested I buy a temperature controller. ARGH this made me mad. In the email I specifically said that the temperature is very accurate and constant, I am worried about the wear and tear of the unit. It really bothers me that they ignored my question and tried to upsell me. I am actually considering switching back to my old Marineland Stealth Pro.


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## Seattle_Aquarist (Mar 7, 2008)

Hi SirKappa,

A filter with higher flow rates might reduce the frequency of on/off cycles. Sounds like a great excuse for a more powerful filter! LOL.


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## SirKappa (Apr 19, 2010)

On a different local forum I was recently enlightened about an Eheim filter with a heater built in!!! It is a great excuse for an upgrade.

/drool


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