# Under Tank Heater impact on Expanding Foam background?



## JoshuaKahnRussell (Feb 12, 2014)

Hello, I am new to this forum and have both a specific question and looking for some general advice. 

Specific Question: I have a 29 gallon corner-shaped vivarium. Both back walls were built with expanding foam + silicone + cocofiber. There is about an inch of expanding foam on each side, and more in some places where there are nobs and such. If I stick an "under tank heater" on the wall for more radiant heat, what will the impact be on the expanding foam? Will it block out all the heat? Is there a possibility that over time the heat can weaken the foam making it more likely to fall off the glass background? Alternatively, if I put the heater under the viv, where there is about an inch of clay balls and an inch of substrate (no water feature, just drainage), will the heater do anything? I am worried about it fracturing the glass underneath if its too hot.

General context advice: I keep 3 milk frogs in this vivarium (just added a week ago). But I made a mistake in building the viv. I put large branches in the expanding foam too close to the top. The mesh area is very small, so I'm limited about where I can place my existing heat bulb on top. It is directly above the branches, which absorb a lot of the heat. I am worried that the right branch will be too hot for the frogs (vine plants that were on the branch directly underneath the heater have shriveled into nothing). The heat distribution in the tank is poor because of this and the range is large: the top of the tank is about 90 degrees F, in order to ensure the bottom of the tank is 72 degrees F. The branch itself is much hotter. My understanding is that milk frogs tolerate about 75-85 degrees F. So far they seem to hang out both at the bottom and the top of the viv, but they stay away from the "hot branch" right under the heater. 

Possible solutions I'm exploring:
1) - finding a plant to put on the branch that is an epiphyte, can tolerate the high heat (at least 95 directly under the lamp), as well as the humidity in the tank (which I am guessing is less directly under the lamp). That's a difficult plant to find as most desert epiphytes that can tolerate the heat cannot tolerate the humidity, etc. Right now my best option is a mistletoe cactus, but I'm not sure it will work 

2) - adding an under-tank heater to the side or top (hence the question above), which will allow me to turn down the heat lamp and maybe solve the problem. 

I'm including a picture of the vivarium for context


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## PDFanatic (Mar 3, 2007)

Put the heating pad under the vivarium. It will not fracture the glass. It will heat any water in your false bottom and then heat your substrate creating humidity. It is effective as I have heating pads under all my tanks that have false bottoms. It keeps the water warm and also keeps my tanks warm as well. It also sounds like you are questioning your build. I know it sucks buy you should probably rip it apart and build it the correct way. This will zero out any chance of fatality. Good Luck...


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## brosta (Oct 25, 2011)

I would recommend not placing the heater on the walls with the expanding foam on them. I did that originally and it caused my background to peel away from the wall. I moved it to one side that does not have any foam background on it and it has been fine ever since. I like it on the side because if it did ever get too warm the frogs can move to the other side which is cooler.


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## JoshuaKahnRussell (Feb 12, 2014)

Thanks so much both of you - this is helpful. I'll stay away from putting the heat pad on the side. Hopefully using it on the bottom will allow me to turn down the top lamp enough that the branch problem won't matter. If not, I'll consider tearing it out


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## Cole (Dec 9, 2013)

I have heat pads under all my vivs and they work nicely.


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## Pumilo (Sep 4, 2010)

PDFanatic said:


> Put the heating pad under the vivarium. It will not fracture the glass. It will heat any water in your false bottom and then heat your substrate creating humidity. It is effective as I have heating pads under all my tanks that have false bottoms. It keeps the water warm and also keeps my tanks warm as well. It also sounds like you are questioning your build. I know it sucks buy you should probably rip it apart and build it the correct way. This will zero out any chance of fatality. Good Luck...


Sorry, that is not correct. You may have had great experiences so far, and I hope you continue to, but under tank heaters can and do crack tanks. http://www.dendroboard.com/forum/parts-construction/78335-under-tank-heater-placement.html


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## PDFanatic (Mar 3, 2007)

I have had my zoomed uth on for months with not a single issue so I will disagree with you Doug. I keep my uth on all the time so it does not cool the water and heat it. I also have a thermostat on my uth so it doesn't just heat to 100 degrees from 55° which would increase the likelihood of cracking a tank. I use egg crate false bottoms not leca...idk but I will stick to what has worked for me.


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## Pumilo (Sep 4, 2010)

You can disagree with me all you want, but you are still wrong. The problem is that you have only your experience to draw on. I have firsthand experience with it happening. The thread I linked you to also provided proof in the form of Ed's first hand experience.
You are stating that it is completely safe.


PDFanatic said:


> It will not fracture the glass.


That is false. I have seen it happen in both dry tanks and wet tanks. Ed has also seen it happen in both dry and wet tanks.
For your statement to be true, both myself and Ed would have to be liars.


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## PDFanatic (Mar 3, 2007)

Yes I have only my experience...which is that almost ten tanks that I have them on...some of which for all winter...haven't had a single problem. That is MY experience so I have posted what has worked for me. I'm sure that we could probably start getting real complex with this if you want Doug. Factors about thickness of the glass, was your tank already drilled and the glass possibly weakened or cracked beforehand. The quality of the glass used blah blah blah. The manufacturer of the glass...we could have hundreds of scenarios and factors.


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## PDFanatic (Mar 3, 2007)

Honestly I don't really care enough to debate the subject anymore. Fact is if I crack a tank it also gives me an excuse to tell my gf why I'm building another tank...which imo is a good thing.


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## Pumilo (Sep 4, 2010)

PDFanatic said:


> Yes I have only my experience...which is that almost ten tanks that I have them on...some of which for all winter...haven't had a single problem. That is MY experience so I have posted what has worked for me. I'm sure that we could probably start getting real complex with this if you want Doug. Factors about thickness of the glass, was your tank already drilled and the glass possibly weakened or cracked beforehand. The quality of the glass used blah blah blah. The manufacturer of the glass...we could have hundreds of scenarios and factors.


I am sorry that you are taking this personally. That was not my intent. My goal is not to prove you wrong. Perhaps I misled you into thinking I wanted to argue, by quoting you. Again, I apologize, that was not my intent.
My only goal here is in answering the OP's question. It's not about you. It's not about me. It is about the fact that glass is very susceptible to thermal cracking. It is about the OP's safest choice. 

To the original poster, I would like to answer your question. Of course you don't have to listen to me. You don't know if I have any idea what I am talking about. My credentials are over 20 years owning and operating a residential window repair service. I'm hands on. I work with glass almost every day for over half my life. Additionally I have years in the hobby and have constructed over 80 vivs from scrap. Many of these vivs are still in use today, by some of my friends, almost 10 years later. 
Regardless of what you may have heard elsewhere, it is NOT safe to say that no tank will ever crack under thermal stress. One tank surviving this treatment, does not make it safe 100% of the time. One hundred tanks surviving this treatment, does not make it safe 100% of the time. 
In the link I provided earlier, both myself, and Ed, provided first hand reports of tanks cracking while using under tank heaters.
In the same link, I explain thermal cracking, how common it is, and what causes it.
Going over all the details here again is really not necessary. Check it out over there, and you know where to find me if you have any questions.


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## Pubfiction (Feb 3, 2013)

Do you attach your under tank heaters directly to the glass or just lay them under the tank?


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## Enlightened Rogue (Mar 21, 2006)

For what it`s worth I`ll add my opinion here. I did at one time have under tank heaters, but it was always in the back of my mind that the glass would crack. Yes it never happened, but when I set up all new tanks I didn`t use them. I purchased a small space heater for my frog room ( a whole 3 tanks) and it works nicely.
I`m a stubborn Italian who didn`t want to listen to anyone, I`ve known Doug and Ed for quite some time, they`re tough but fair and never give out bad info.
So, they`re your tanks and you`re free to do as you want. For me it wasn`t worth it to 
push my luck a second time around.


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## Coqui (Jan 17, 2013)

I have had great success with UTH on the bottom of
My Exo tanks. However, you do take a chance when
You place them there. I have seen my friends tank's bottom cracked
From an UTH. The manufacturer also warns from placing
Them under the tank. I believe they make a very low wattage 
One for a rain forest type tank. Problem is not enough heat. I will 
Suggest if you go with the bottom use a thermostat to control the
Heat. 
Good luck.


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## Judy S (Aug 29, 2010)

for the poster who has had luck...a carefully chosen word...with the undertank heaters...are the tanks somewhat elevated above the pad, or directly on it. Would that make a difference...good/bad? If you have sufficient water in the substrate, why not an aquarium type heater that would be buried in the hydroballs, or whatever...and just be available for the colder seasons? I just cannot imagine how someone would feel coming into their "frogroom" and finding a wrecked tank with dead frogs...


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## Pumilo (Sep 4, 2010)

Of course everybody can make their own choice. It is a good thing to be able to weigh the risks and benefits of any decision, and make their own choice. I don't have a problem with that.
My problem comes when there is a proven risk, and somebody recommends to a new frogger that it is completely safe. That is YOUR risk to take and YOUR decision to make. 
In my book, it is simply not ok to weigh that risk yourself, and then proclaim it to be 100% safe. The person looking for information has the right to know the risks. 

Personally, if I give out information that kills a friend's frog, I'm going to feel pretty bad. If somebody asks me about something that I know to be 99.9% safe, I'm going to point out the .1% risk every time. It's (usually) not meant to personal, and it wasn't meant to be personal this time. I know, I upset a few people sometimes (understatement), but I like to think I may have helped a few frogs out.


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## latieplolo (Feb 12, 2014)

I'm new to frogging, but I've had hermit crabs for 7 years and I've used UTHs on a number of different sized tanks. I always used them on the side so that no buried molting crab would burn up. I think heaters on the side aren't as harsh on the glass because the heat is also escaping out the sides, whereas placing a heating pad underneath directs all of the heat directly up into the glass (heat rising and all). But then again, you're wasting some energy that way. I've never had a problem with glass cracking, but I have noticed that heating pads left on constantly will sometimes get to crazy hot temperatures for no reason. I think if you get a couple small pads rather than one big one, the risk will be less.


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## Enlightened Rogue (Mar 21, 2006)

Judy S said:


> for the poster who has had luck...a carefully chosen word...with the undertank heaters...are the tanks somewhat elevated above the pad, or directly on it. Would that make a difference...good/bad? If you have sufficient water in the substrate, why not an aquarium type heater that would be buried in the hydroballs, or whatever...and just be available for the colder seasons? I just cannot imagine how someone would feel coming into their "frogroom" and finding a wrecked tank with dead frogs...


Hi Judy, you stick the heating pad directly to the bottom of the tank and they usually 
provide little stick on spacers you put on each corner of the tank so the bottom has some 
air flow. The heat isn`t instant as some people think. When I was using them it would take
hours to raise the temp a few degrees.
Again I`ll say I never had a problem but I didn`t want to risk it again.


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## Judy S (Aug 29, 2010)

thanks...I was wondering whether direct contact with the glass was part of the tank failure...but was concerned about the weight of the tank being a serious issue....wonder whether during some exceptionally cold spells whether an electric blanket(s) OVER the vivs might be a real help...why not???


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## Enlightened Rogue (Mar 21, 2006)

My tanks are on the 2nd floor of my house and it gets pretty cold up there. They just put $900.00 of oil in my tank so keeping the house thermostat fired up is not an option. I really only use the space heater at night when the heat in my house is turned down really low. The house warms up during the day so I don`t need it then plus I don`t like using the space heater when no one is home.


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## Judy S (Aug 29, 2010)

see, that's why people believe "New Englanders" are cheap....


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## punctata (Jan 31, 2011)

Can I ask what that green mossy stuff is? If it is the moss that I am thinking of like the kind petco sells that is green and is loose. You may want to remove it as Milks will lunge at food. This moss can cause impaction very easily. It is very common with tree frogs. A cricket is on the moss and the frog eats the cricket along with a mouthful of moss.


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## Pubfiction (Feb 3, 2013)

I would imagine if you put an under tank heat under the tank but did not attach it directly to the glass you would significantly reduce the risk. But I don't know if that is what people are doing or if they are sticking it to the glass. 

As for the fish tank heater suggestion, those things also fail, and they tend to fail in the on position cooking everyone's fish. Fish tank heaters are also designed to go where their is some water circulation. So I have no idea what the outcome would be if you had them in a stagnant semi insulated area like the drainage layer. What I do know is if it fails in the on position you could cook the water and your frogs. However if your tank cracked from an under tank heater then most likely you would just come home to find water all over but not dead frogs. 

Also all under tank heaters are suppose to have space under the tank. They should come with stand offs. For an exoterra this wouldn't be needed but for other tanks you need to make sure its elevated.

One thing I do know is that the heating situation in the PDF hobby is not in good shape. Seems to be an issue we have not found a good solution for.


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