# Hydor 15W mini heater - does it work?



## tuonor (Nov 26, 2009)

Purchased one of these nano heaters for a 6 gallon nano. Figured others might be interested in some test data given it seems like these units have worked for some and not at all for others.

Comparing versus a Visi-therm Deluxe 25W traditional submersible which seems like the logical alternative given it is the shortest tube style heater I could find.

Size comparo (just over 5" vs. just over 7" for the Visitherm):










Test rig
- Started with 2.5 gallons of water in an Ikea storage bin
- Hydor Hydroset digital thermostat with in-water probe
- Oregon Scientific clock for ambient air temperature


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## tuonor (Nov 26, 2009)

Hydor rates the 15W version to raise the temperature of a 5 gallon tank by 5 degree F. I left the setup overnight with the heater on all night and then snapped this photo in the morning:










The 15W is good for a remarkable 0.2 degree difference in 2.5 gallons of water, meaning it is essentially useless (and yes, if I put my hand on the heating element heating there is some perceptible heat dissipation so I don't have a dead unit).

Pretty disappointing versus the Hydor spec; going to run the Visi-therm to see how it does tomorrow.


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## tuonor (Nov 26, 2009)

*25W Visitherm*

Next up: 25W Visi-Therm submersible.

I moved the test rig to the laundry room which is a more rigorous workout because the door seal is a bit leaky. 










Plugged in the Visi-Therm and left it overnight with the thermostat set at max. Overnight, was able to establish a 11 degree differential (78 degree tank temp vs. 67 degree ambient air temp. Works as it should.


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## tuonor (Nov 26, 2009)

I decided I may have been unfair to the Hydor in that it may take more time to raise the temp of a tank than I allowed originally. Perhaps it can hold a higher temperature given more time.

Thus, I put in the Hydor 15W in the 2.5 gallon test rig, after raising the tank temp to the high 70s with the Visi-Therm. I let this sit for several days to allow it to equalize. 

Net on 2.5 gallons, it looks like a 6 degree temp differential is defensible with the 15W Hydor. I just don't know that I'd trust it to hold if there was a meaningful fluctuation within 1-2 days:


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## tuonor (Nov 26, 2009)

Last test. Increased water volume to 5 gallons and allowed the Hydor to work for a few days.










After 3 days, I checked the delta, the hydor was able to hold a 3 degree differential (72 degrees vs. 69 degrees).


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## tuonor (Nov 26, 2009)

*Conclusions:*
These are the factory spec on the Hydor relative to my results. Net, I think the 15W version of this heater I tested might be appropriate for a 1-2 gallon nano but wouldn't do anything meaningful for the rated 5-10 gallon tank. My guess is the 7.5W version would only work for a fish bowl.

Mini 15W Hydor
*2.5 gallons:* Hydor spec (na); my result (+6 degrees)
*5.0 gallons:* Hydor spec (+5 degrees); my result (+3 degrees)
*10 gallons:* Hydor spec (+4 degrees); my result (didn't test given result in 5 gallons)

EDIT: I discovered a few months after doing this test that the volume of water in the second test was 4 gallons not 5. This means the shortfall of the Hydor vs. spec is a bit bigger than I thought (ie factory spec is +5 degrees in 5 gallons, but my result was +3 degrees in 4 gallons).


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## accordztech (Dec 6, 2004)

nice man good effort.

I have that mini 7.5whydror. I did a little test of my own. In 5 gallon tank it rose it like 2 degrees from 66. Then i put it in my 1.2 gallon tank, rose that sucker to 78 from i think 68. Basically my betta is warm now lol.

its a OK heater, sits there...i try to shove it under the gravel. 

I also think that you can get a higher temp if you put a lid on your setup just like a fish tank.


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## JamieH (Sep 20, 2006)

would be very interested to see how the hydor performs when you aren't using convection alone to circulate the heat i.e. add a small pump.


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## jmhart (Mar 14, 2008)

accordztech said:


> I also think that you can get a higher temp if you put a lid on your setup just like a fish tank.


A lot of people don't have lids on nano tanks, so I think in order to a viable option as a heater for planted nano tank use, it shouldn't matter whether the tank has a heater or now.


OP, great write and review. The data speaks for itself.

It's a little shocking considering how well other Hydor products work.


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## GTR (May 27, 2009)

That test would require an air pump for circulation. Some small powerheads might actually add more heat to the water than the heater does. lol

SteveU


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## bcdudley (Nov 18, 2009)

Other things that could be influencing the test may be that it is sitting on a cold tile floor ( yes, I see the rug in between). The floor is going to act like a chiller. Also, the surface area of the container is much larger than a standard nano tank would be. You will loose some heat to evaporation using a container this big. Last thing, and it was already mentioned is there is no circulation in the tank. To be able to consistently heat the water, the heater needs water moving around it. Otherwise, it will heat the water only in the immediate vicinity of the heater and shut off.

I think it is great that you are putting forth the effort to inform people of these heaters. Please just take this as a helpful suggestion and not negative criticism.

Thank you.


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## houseofcards (Mar 21, 2009)

I recently put a 15g Hydor mini on my Mini S (3.5g) and it rose temp around 7 degrees. Temp was around 68 at night now holds steady around 75.


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## jmhart (Mar 14, 2008)

bcdudley said:


> Other things that could be influencing the test may be that it is sitting on a cold tile floor ( yes, I see the rug in between). The floor is going to act like a chiller. Also, the surface area of the container is much larger than a standard nano tank would be. You will loose some heat to evaporation using a container this big. Last thing, and it was already mentioned is there is no circulation in the tank. To be able to consistently heat the water, the heater needs water moving around it. Otherwise, it will heat the water only in the immediate vicinity of the heater and shut off.
> 
> I think it is great that you are putting forth the effort to inform people of these heaters. Please just take this as a helpful suggestion and not negative criticism.
> 
> Thank you.


if it were a stand alone test, that would all be true, but since it's compared against a comproble heater in the same conditions I think it is still valid.


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