# A reptile under tank heater + temp controller = concealed aquarium heater?



## cbachmann (Aug 6, 2013)

Never tried it myself, but I've heard it can crack the bottom. furthermore, I feel like it might make the guys at the bottom uncomforable, as well as hurt root systems, by creating an unnatural temp gradient (i.e. the gravel is gonna be the warmest part of the tank, as opposed to the water column)


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## Texan78 (Nov 17, 2013)

I like the logic but I think you are assuming putting this on the outside back glass or under the tank? 

It definitely wouldn't work on the inside and on the outside I don't think it would be strong enough to radiate heat through the glass. Not to mention battling the ambient temps in contact with the tank from the other sides. For example, with an in tank heater the water may be 80F but if you feel the glass from the outside does it feel 80?

What are those rated at anyways, like 30 watts?


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## datsunissan28 (Sep 27, 2013)

I've used hearing cables for a few smaller tanks. They were hooked up to an external thermostat. Those tanks hold temperature fairly well and cycle on and off less often then my other tanks. 

In theory it's the same idea. Some stands are open at the bottom and provide all the support at the edges. This would probably work best as you wouldn't have to worry about the cord or the heating pad burning the stand. 

The cost of a thermostat is usually the price of a typical aquarium heater though.


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## Bushkill (Feb 15, 2012)

Heating cables would be the best alternative. From everything I've read, they function very well. I don't think one cable will service more than a 10G, but I could certainly be wrong; but you could always use 2 on a larger tank.

Reptile heat mats aren't meant to be covered completely.


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## TekWarren (Oct 6, 2013)

I've used/work with heat pads and heat tape type products for years with reptiles but never tried it with aquariums. I would think if it was more efficient/safe more people would be doing it, it's not a new idea. My concern like others would be the heating element in direct contact with the glass. Most thermostat's would be either ON or OFF based on temp reading. I don't know if the glass can take constant on/off heat like that or if it would be harmful. The other thing to consider is efficiency. Will the heat transfer through the glass and through your substrate in an efficient manner as apposed to heating circulating water directly? -I have my doubts unless you can somehow seal the heating element to force radiation up and through but glass isn't the best heat conductor.


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## PlantedRich (Jul 21, 2010)

Since you are speaking of using it with a controller, how about an immersion heater? This is a cheap one, way over sized for the tank (200W ) but there may be others along the same line. Still in the tank but easy to hide?


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## lochaber (Jan 23, 2012)

I don't think it would work very well.

Reptile heaters are typically used to make a warm spot, not heat the entire space.

Also, water takes a lot of energy to heat, and with this style heater, it has to pass through the glass, and through the substrate (which can be a very effective insulator). I think this will mean that not only will the tank not be adequately heated, but as stated above, you will also have a very steep temperature gradient, with it getting noticeably hotter through the lower reaches of the substrate, and very hot on the outside of the tank bottom.

I think the best option would probably be to use some sort of in-line heater, to hide your heater behind hardscape, get a heater that blends in (camouflage-black heater on black background, in shadow, etc.), or to stick it behind a mattenfilter or something.


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## MlDukes (Nov 24, 2009)

Thanks all for the input. Stopped by the lfs today and the large (11"x17") heat pad is only 24w.


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## Eddie_42 (Dec 18, 2013)

I doubt that 24w pad would put out enough heat. Even a 10gal tank needs a 50 watt heater. Thats what i have now, and its on a fair amount of time. Ambient air is between 68 and 72 in my house at the moment. Between the loss of energy from the glass transfer, and the heat loss from the other walls of the tank, I think this heater would be on full time.

With that assumption, I dont think cracking would be an issue. the glass would reach a stable temp and maintain it. The issue with cracking (coming from a purely scientific approach) is rapid temperature change. if the tank cools, and thus the glass, and the heater kicks on, full force rapid heating, it can cause stress in the glass. The outside expands, the inside doesnt....crack.

Use of glass is often achieve in heating because its thin. Lets freeze one beer mug, and one wine glass. If you then pour boiling water into each, the wine glass is far more likely to survive...less material to expand. For the 10g and below tanks, I think the glass is thin enough to react in time. 

addressing the '1st obstacle': To work under that assumption this was possible (and i dont advocate it). You would need a thermostat in the tank, that fed into an electrical interrupt for the heater. Then when the water reached the right temp, it shut off the heater. and visa-versa. 

Hope this was illuminating...i have a thing for science questions. Hope i didnt bore or confuse you.


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