# Hydor In-Line Heater Issues?



## OVT (Nov 29, 2011)

In my experience, switching on and off is unusual. I would call Hydro and ask for a replacement.


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## Seattle_Aquarist (Jun 15, 2008)

Teebo said:


> So I finally got my external filtration system up and running on my 15 gallon (canister, pump, CO2 reactor, UV sterilizer, heater) yes it is a bit overkill for 15 gallons but it is a display tank. I bought the 1/2" Hydor 200W model since it was the smaller, but 200W is too much for a 15 gallon I think. The problem is it cycles on and off literally every other minute. I can see how this would maintain a very accurate temperature but I would think it will shorten the life of the heater which is not cheap. I have already noticed jumps in my power bill from 25-50W aquarium heaters so I will be curious to see what this does. Is it worth running a standalone temperature monitor or is it just a waste of money? Will it run my heater more efficiently? Is there a way to somehow use a voltage regulator between a temperature monitor and my heater to throttle down the heater consumption? If this unit dies on me within 1-2 years I will replace it with a DIY in-line sleeve of some sort that accepts a heater of my choice.


Hi Teebo,

Yes, your Hydor 200 watt is oversized for a 15 gallon aquarium but I run the 200 watt model on my 20 gallon tank with no issues. I think that your problem may be the amount of water flow through your heater. I run a 220 gph canister filter on my 20 gallon and the only in-line item is the Hydor ETH heater.

First of all did you install the heater in the vertical position as recommended in the instructions? It is important for it to be vertical to insure proper operation.

It appears that you have a lot of "in-line' stuff going on. I assume that your canister is not self-powered and that is why the pump is part of the in-line equipment? If I read your post correctly after the pump you have a CO2 reactor, U.V. sterilizer, and then the Hydro heater? With all of that equipment 'downstream' from the pump I would suspect a highly diminished flow rate. Depending upon the CO2 reactor type it may be a 'straight-through' that typically only slightly diminishes flow or if a Cerges or Grigg reactor it can have a greater effect. U.V. sterilizers are notorious for restricting flow. The 'turbo-twist' designs to maximize dwell time for the water to be exposed to the U.V. light along with 90 degree angles for the hose connections in some cases can drastically reduce flow.

Typical U.V. 'twist' design









If it were me I would remove the U.V. from the in-line sequence and see if the issue of 'excessive cycling' of the heater improves or goes away completely. You can always run the U.V. on a separate (likely much smaller) pump that is sized to maximize 'dwell time' for the U.V. unit.


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## PlantedRich (Jul 21, 2010)

I would also highly recommend using a separate controller. A 200 watt heater sticking on will overheat a 15 gallon in a couple hours or so. Definitely less time than most of us are gone from home. I found a 50 watt killed a ten gallon overnight. 
With a controller, you will have far better control if it is needed but the major advantage is that you have a separate piece of equipment to save the fish if one fails.


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## Teebo (Jul 15, 2015)

My heater is in an almost vertical position it is on an angle a little bit though. Is this okay? I hear it 'click' on and off every other min it is annoying. 







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The canister I have is a tiny SunSun so I bought an ECO 396 pump and connected it between the canister and CO2 reactor so that it pulls from the bottom of the canister and pushes it up into the reactor. My flow rate is so high even with everything in-line I have to throttle it down with a ball valve, that Eco 396 is a powerful pump! The UV I have I do not think has any internal twisting fins. 


























The flow rate in my opinion is not the issue because I can change that with the valve, I will see if full open makes any difference. I will say I did not plumb in a bypass path to reduce the flow through the UV as some people have suggested, but I may eventually.


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## Seattle_Aquarist (Jun 15, 2008)

Teebo said:


> My heater is in an almost vertical position it is on an angle a little bit though. Is this okay? I hear it 'click' on and off every other min it is annoying.
> 
> The canister I have is a tiny SunSun so I bought an ECO 396 pump and connected it between the canister and CO2 reactor so that it pulls from the bottom of the canister and pushes it up into the reactor. My flow rate is so high even with everything in-line I have to throttle it down with a ball valve, that Eco 396 is a powerful pump! The UV I have I do not think has any internal twisting fins.
> 
> The flow rate in my opinion is not the issue because I can change that with the valve, I will see if full open makes any difference. I will say I did not plumb in a bypass path to reduce the flow through the UV as some people have suggested, but I may eventually.


Hi Teebo,

The pictures sure help to see what is going on, thank you!

I think that the heater is close enough to vertical to not be an issue.

I see the valve before the water enters the SunSun canister is partially closed; is this the valve that is your main flow control? Let us know if increasing the flow results in a decrease of the on/off cycling you experience with the heater.


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## PlantedRich (Jul 21, 2010)

I think you are on the correct path with the thinking by Seattle, here. 
But then we are having a small discussion of another point that you may want to check before deciding the heater is defective. 
Several of us have had experience with various heaters that have solid state circuits acting bad when they are near other electronics. Various types of electronics, especially tube light ballast and older style motors put out electro-mechanical interference (EMI) that can bleed over into other electronics. Radios used to get a pop and crackle at times but they have improved that problem. AM car radios used to pick it up from the ignition. 

It might be worth the time to try some moves of the heater away from things or if that is hard to do, try shield like metal between the heater and other electronics to see if you might be dealing with one of those weird things. It might be easier than sending things back with all that involves.


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## Seattle_Aquarist (Jun 15, 2008)

Hi PlantedRich,

The Hydor ETH does have an electronic thermostat so electronic interference is a possibility.

Photo borrowed from Jason Baliban's website Project Aquarium


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## N2uqs (Apr 6, 2016)

If it is RFI interfering with the switch try using a few snap on pieces of # 43 ferrite.


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## Teebo (Jul 15, 2015)

Thanks everyone - I do not think it is interference I believe I have eliminated that possibility. See below



Seattle_Aquarist said:


> I see the valve before the water enters the SunSun canister is partially closed; is this the valve that is your main flow control?
> 
> Let us know if increasing the flow results in a decrease of the on/off cycling you experience with the heater.


Yes I am using the valve on top of the canister to throttle the flow, only because that is how it was setup with the stock pump. Apparently restricting the vacuum side must be better than the pressure side, although I can do it on that side as well with that blue ball valve between the UV and heater. That T-off with the secondary ball valve is for water changes, it will be (somehow) attached to a venturi syphon valve like this so that the pump will start my syphon for water changes I hate throwing fresh water down the drain using these things. 










Okay so I setup a video camera on a tripod and shot the light on the heater for an hour on full flow and an hour throttled down. Interesting results when the video was sped up, when I have it throttled down the heater only turns on for 1min at a time and it remains off for 3-7min. When I open it up all the way (which is very strong flow) the heater turns on for 5-6min at a time! Then it remains off for 5-10min, this is to heat the tank to 76F ~2F

The reason I am not running it unrestricted is because my return head is not low enough so I get excessive splashing, I need to customize something to drop it down for riparium use.


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## OVT (Nov 29, 2011)

You might want to restrict filter's on the outflow side, not on the intake. The idea being that you want the filter full of water and increased dwell time with the media is a plus.


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## Clear Water (Sep 20, 2014)

Never ever restrict your flow on the intake side of your canister.

I would have thought that your head height would have been the problem with your heater but you seem to think you have to much flow. I seem to me that if water flow may have some kind of effect on how long the heater runs that it has to be effect by water flow. I just wonder if it to much heater for the amount water flow thru the unit. I use around 100 watts for 20 gallon with no problem keeping the tank at temp. The other day I had unit flash to the highest setting the tank only made it to 84 degrees. I sorry but I don't like in line heaters if your pump fails your heater fails too.


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## PlantedRich (Jul 21, 2010)

Sounds like you may be getting close to solving the mystery so my idea is likely not the cause here. But as info we made need at some point, I ran into a bit of more indication that EMI/RFi can become a problem to sneak into the hobby. 

I'm always shopping for heaters it seems and came across looking at the Neotherm brand. 
This is a part of their info which I cut and copy: 

SPECIAL NOTE for use with Aquarium Controllers:
APEX users: Please be sure to plug your Neo-Therm into plug 4 or 8.
Digital Aquatics users: Neo-Therms can be plugged into any port without issue.

The point being that we may all need to become more aware when we get something flaky in our equipment?

On the point of where to restrict flow, I have some doubt that it really matters much. If water can't come in, I don't see the pump on filters being strong enough to create the vacuum when water is pumped out. I feel like it will just not move water as mag drive filter pumps are notoriously weak on torque. In my experience, when the impeller is out of water, nothing happens. It just spins until water returns. I do restrict mine on the output but I don't really believe it matters.


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## Seattle_Aquarist (Jun 15, 2008)

Teebo said:


> Thanks everyone - I do not think it is interference I believe I have eliminated that possibility. See below
> 
> Okay so I setup a video camera on a tripod and shot the light on the heater for an hour on full flow and an hour throttled down. Interesting results when the video was sped up, when I have it throttled down the heater only turns on for 1min at a time and it remains off for 3-7min. When I open it up all the way (which is very strong flow) the heater turns on for 5-6min at a time! Then it remains off for 5-10min, this is to heat the tank to 76F ~2F


Hi Teebo,

So basically at the increased flow rate the cycling decreased? It makes sense, at a low flow rate the water inside the heater reaches the pre-set temperature quickly and then cycles off. Once sufficient cooler water has entered the heater and cooled down the thermostat the heater turns back on. At a higher flow rate the cooler water is entering the heater faster making it more difficult for the heater to hit the pre-set temperature. 

How often should it cycle? That will depend on the flow rate through the heater and the difference between the room ambient temperature and the tank temperature, the tank volume, and the temperature you set the heater for the tank. My experience has been that at a given temperature a small tank will heat more quickly and cool more quickly than a large tank.


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## Teebo (Jul 15, 2015)

Wierd how the stock setup said in the directions to restrict the intake on the canister. 

Well regarding my original problem maybe it is not a big deal that it cycles more at a lower flow rate, I assume the heater will last just as long. A big downside for me is the loud clicking of the relay inside the heater.


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## payluder (Feb 3, 2016)

I have the 300w with the eheim 2217 and the rex reactor going to my 17 gallon and I rarely see the heater go on. I set my temp to 74


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## PlantedRich (Jul 21, 2010)

Teebo said:


> Wierd how the stock setup said in the directions to restrict the intake on the canister.
> 
> Well regarding my original problem maybe it is not a big deal that it cycles more at a lower flow rate, I assume the heater will last just as long. A big downside for me is the loud clicking of the relay inside the heater.


I might tend to disagree with how the heater may last? 
The clicking is a relay closing and that relay will have contact points on it. On heaters with open contacts and clear glass we can see they often make an arc (flash) when they close/open. This is kind of like a tiny little arc welder and makes a little burn on the contacts each time. So the more often they open/close, the more quickly the contacts burn. 
When I tear down defective heaters, I rarely find the heating coil is open like it "burned" in two but I do often find heaters that have defective contacts. 
That leads me to favor a heater which is just big enough to keep the tank steady rather than a short cycle time.


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## Seattle_Aquarist (Jun 15, 2008)

Hi Teebo,

+1 for PlantedRich's comment, the less cycling off and on the better for the longevity of the product.


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## Teebo (Jul 15, 2015)

Totally understandable with the physical contact of the relay, when the heater dies I will replace the relay. Better yet if I set the temp to max and use an external controller the relay will be used less right? So if the relay in the controller dies I can unplug it and use the heater as is until the controller is replaced? Maybe the relay will still click if the power is removed from the heater, even if set to max it will click when power is supplied back to the heater?


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## jrygel (Jan 29, 2014)

PlantedRich said:


> SPECIAL NOTE for use with Aquarium Controllers:
> APEX users: Please be sure to plug your Neo-Therm into plug 4 or 8.
> Digital Aquatics users: Neo-Therms can be plugged into any port without issue.


For what it's worth, this is needed for Apex because they use a solid state TRIAC relay on outlets 1-3 and 5-7 that becomes inconsistent with loads of less than 10 watts or so. Outlets 4 and 8 are standard mechanical relays that will work at any wattage.



Teebo said:


> Totally understandable with the physical contact of the relay, when the heater dies I will replace the relay. Better yet if I set the temp to max and use an external controller the relay will be used less right? So if the relay in the controller dies I can unplug it and use the heater as is until the controller is replaced? Maybe the relay will still click if the power is removed from the heater, even if set to max it will click when power is supplied back to the heater?


Your best bet is to set the temp in the heater to something higher than your set point but not high enough to kill your fish, and use an external thermostat to control the temp. This way:



The external thermostat is the one doing the cycling, the internal will be on all the time.
The internal thermostat acts as a backup - if the external gets stuck on, the internal will kick in to regulate temp to it's higher set point.
The external thermostat will be reading from a point in the tank, and the temp of the actual tank will cycle more slowly than the water within the heater body, so cycling should be reduced.


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