# Newbie - Thermal Gradient Issues In Bearded Dragon Viv



## ClemSnide (Jul 23, 2013)

Hi All,

First post so please be gentle with me.

I am taking my first tentative steps into the world of reptiles and am in the process of getting my set up correct.

I will be keeping a Bearded Dragon, but not until I am sure everything is setup correctly.

I have a 4x2x2 Vivexotic. I got a decent deal on the cabinet and starter kit so went with that. It iis the new version with supposed better ventilation in the doors.

I have everything put together and have laid slate tiles as substrate. There is a java wood hide and branches to raise the basking spot closer to the lamp.

My issue is that I just can't get the thermal gradient right. I am using a Habistat dimmer to assist but things aren't settling correctly.

The cool side of the Viv is registering around 85.5 - 86 degrees and if I try and adjust the stat to lower it I loose the temp under the basking spot. It drops to around 93.5 - 94. The lamp itself then switches itself off or barely registers at all.

The habistat probe is around 2-3 cms off the floor slightly towards the colder side of the viv.

I have read so much conflicting info around temps that I feel like my head is going to explode. So a definitive on what temps I'm looking for would help. I have been trying to achieve a 20 degree spread 84 - 104 is that ok?.

The only way that I have been able to get what many care sheets suggest are ok temps 83.5 - 84 cold 103 - 104 basking is to open the cold side glass door by around 3 inches and let some air in. 

Do people think I am doing something wrong or am I suffering with the current hot weather? My living room is pretty warm and this am after no heating at all overnight the viv temps at either end were 77.5.

I'm using a 100w basking bulb which came with a porcelain reflector. At present one digital thermometer probe is placed in the middle of the basking spot and the other on the wall of the cold side again 2-3cm off the floor.

Both myself and my daughter are keen to resolve this asap as we want to bring the Beardie we have left a deposit on home. I won't until I am sure I am not going to do anything detrimental to its health.

Apologies for the ramble but I've tried to put as much info in as I can.

Any help you can offer will be welcomed.

Cheers.


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## TheGuvnor (Apr 26, 2013)

Hi mate. And welcome to these forums:welcome1:.

Ok mate, Im guessing your in the UK yea?. If so, you will probably need like a 40w bulb in the basking spot.

By the sound of things, you have the same Viv as me. the VivExotic Extra Large. A really great viv.

I have my Dimming stat prob about 2 inches off the floor in well into the cool end. Its about 3inches from the cool-end wall (if that makes sense :whistling2.

I get really steady temps (26/28c cool & 40/42c Basking). Although in this crazy UK heat, everyone is struggling, so I wouldn't panic to much. You will probably only get a decent basking temp etc for the first few hours of when your lights come on. And then, like most, the light will just dim to nothing.:devil:

I did have to tweak my basking spot a bit when I first got the viv. I have my basking bulb bracket attached to the side of the viv with industrial Velcro. So I can higher and lower to raise or lower the basking temp with ease, without the fear of it ever falling.

But dude, post a picture of how you have it setup. It always help when the guys n girls here give advice.

And if anything else you want help with, just ask dude.:no1:


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## ClemSnide (Jul 23, 2013)

Thanks for the reply. Went out and got myself a 50w basking bulb today. Put it in when I got home from work. Viv has been off all day and now been running for 1hr 45mins. 

Temps are still playing up a bit. I have the Habistat set to 26 degrees and have moved the probe to within an inch of the cool side wall. Cool side is showing 84.5 and basking spot 104.3. 

What I don't understand, is with the Habistat set to 26 why, as is currently the case the heat lamp is still on and looking at the bulb, still running at around 75% power. Shouldn't it have dimmed down at the point that the cool side hit 26 (79)?

If I shift the Habistat down to 25 it kills the light almost completely and the basking spot temp drops off very quickly.

Given that many others have said that this is a decent Viv and the Habistat is tried and tested, I can only assume that I am doing something wrong.

Any further advice people can offer would be appreciated.


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## Hannah81 (Nov 19, 2008)

Thermostats are not calibrated. The markings round the dial don't mean squat tbh. This is why you use a thermometer inside the viv to set the stat with, ignore the dial numbers and go with what your thermometer says.


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## ClemSnide (Jul 23, 2013)

Thanks for that. Good to know that the stat isn't faulty.

Really have no idea what is going on. The basking spot temp has dropped from 104.3 to 97.9 in around 10 mins and the bulb is now barely on at all.

In the same time the cool side has gone up from 84.5 to 84.9.

Really don't understand how that can happen!?!

Apologies if I am sounding thick here but this really isn't making much sense to me!

If I move the stat up 1 degree it will fire the bulb up again and raise the basking temp but that is just going to raise the cool side even further isn't it?.


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## TheGuvnor (Apr 26, 2013)

Mate. I'm guessing your room temp is high like most of us here in UK. As it's dam hot. 
You won't have much joy at all in this weather. The bulb well probably be off 90% of the day. What you have done is correct. But honestly, the more you fiddle with it the more frustrating it will be for you. 
You will see on a cooler day what you have done is correct. Keep that stay probe in cool end.
And yes, raising the stat up 1 will obviously make the bulb come on again. But once the cool side gets the heat the bulb well dim until it's cooler, and it well brighten on its own again. It's all to keep that cool side safe.

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## ClemSnide (Jul 23, 2013)

Thanks for the reply. Your right, fiddling with it is properly doing my head in. Not half as much as my wife though, I'm driving her crackers going backwards and forwards to the viv to check temps!.

Anyway, things seem to be settling a little bit at present and have been holding at 103.4 basking and 84.2 cool.

I'm not going to touch it as that seems, correct me if I am wrong, to be within safe tolerances and it doesn't sound like I'm going to get much better with the way the weather is at the moment.

At present I am only offering two basking levels, floor or 6-7 inches from the lamp, will be addressing that with a couple of smooth rocks and then hopefully should be good to go.

Once I get a chance I'll try and post some pics of my set up as I'd welcome comments on whether it looks ok.


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## TheGuvnor (Apr 26, 2013)

Sounds good mate. I know it's hard to not fiddle. But like I said, in this weather you just won't be happy with what you see. And remember, the stat is there for safety. To give your Dragon a cool side to escape to. And those temps are fine. You will find the cool end well be around 26/28c in the cool weather. All fine mate.

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## ClemSnide (Jul 23, 2013)

Finally bought her home today. Have to say, I have been amazed at how well she has settled in. She allowed me to handle her in the shop and also for 5 mins before I put her in the viv - no struggling at all.

I was expecting her to run off and hide for a few days. She has been very inquisitive. Exploring all over the viv, has found her basking spot and is currently chilling out there.

I wasn't planning on feeding her today but she spotted the box of locusts as I was putting it away and went crazy. She guilt tripped me into feeding her 3!. She has also munched her way through a calcium powder dusted Beardie Salad - shop owner said she had been fed just before I collected her, so not to worry too much about feeding her. That went out of the window.

Was told she is 5-6 month old. Gave her a good check over and all looked good.

Was out for a couple of hours this afternoon and my wife and daughter have been sitting talking to her, she is already jumping down from the basking spot and showing off at the glass when you walk past - I'm under no illusions that she is only doing it at the moment, because we are seen as a food source, but it is nice that she seems so active.

Will post up some photo's of the viv set up and her shortly. Would appreciate your views on the set up. I am going to add a rock to give her 2-3 basking levels and am hoping to pick up a few pieces of slate tomorrow.

Cheers.


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## TheGuvnor (Apr 26, 2013)

Sounds great. Can't wait for the photos. 

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## ClemSnide (Jul 23, 2013)

Ok, pictures should hopefully be attached. 3 of the viv and 2 of Mildred (my daughter chose the name!!!)














































*Second go. Hopefully they should work this time.*


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## TheGuvnor (Apr 26, 2013)

Cant see any pictures dude. Dunno if thats your end or mine.


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## ClemSnide (Jul 23, 2013)

Hmmm. Not sure what is going on there. In Chrome if you right click on them and then say open in a new tab they seem to work.


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## TheGuvnor (Apr 26, 2013)

Working now. Weird. Nice looking dragon. Looks very inquisitive 

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## Jeffers3 (May 18, 2010)

At the risk of getting shot at (again!), you have the thermostat probe in the wrong place. This won't help with getting a gradient, particularly when the ambient temperatures are quite high. Let's think about what is happening in your viv:

The heat source is heating the warm end of the viv. Agreed?

The cool end will receive heat from the warm end. Agreed?

The heat it receives will be from conduction, radiation and convection. Agreed?

Conduction is slow and negligible. Radiation should be low, as the heat source is focused on the basking spot. Therefore most heat transfer is by convection. Agreed?

Your heat source will be heating the basking area by radiation, creating a hot spot. Agreed?

The hot spot will then emit heat via convection, which will rise and pass along the top of the viv, towards the cool end. Agreed?

The bottom of the viv at the cool end is the last part of the viv to receive heat, so there will be a huge time lag. Agreed?

The vents in your viv should be designed to remove heat by sucking in cooler air at the bottom, as the warm air is passed out of the top. This assists in setting up the thermal gradient from the warm end to the cold end. Agreed?

This increases the time lag from the heat source switching on and the cool end warming up. Agreed?

Worse still, even once the heat source is switched off, there is still a huge amount of residual heat that will continue to move towards the cool end, due to the time lag. Agreed?

If you place the probe where it should be - towards the warm end, you can control the warm end temperature, without a huge time lag. Agreed?

You can then rely on the set-up and vents to do their job and help create the gradient (they're not the only means of heat loss). Agreed?

During times of extreme ambient temperatures, it will always be difficult to set up a gradient without a cooling mechanism at one end, though. A fan can be used to draw air out of the upper vent in the cool end, which will help a bit, but something like a small peltier cooler is the only real answer.

I know the argument about using the thermostat probe to "protect the cool end", but I'm afraid that's like using the thermostat in your oven outside the oven to make sure the kitchen doesn't get too hot!


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## TheGuvnor (Apr 26, 2013)

Keep it where it is my friend. It's better for your dragon in the cool end so he has a Cool area to escape to. If in the hot end the whole Viv will be the same heat. Not good. 

A stat IS a safety feature, NOT a control device. 

Have a read here Safe Setup of Thermostats for Basking Animals - Hades Dragons UK
It explains if you need it explaining, and goes through some of the "misconceptions" like in the above post :whistling2:, but if its working for him, then that's fine.

But, at the end of the day, Do what you want. I'm just trying to help, certainly don't want to get into the stat debate AGAIN. But I guarantee you, I'm one of probably 99% of the other users here who have the probe towards the cool end.


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## Jeffers3 (May 18, 2010)

TheGuvnor said:


> Keep it where it is my friend. It's better for your dragon in the cool end so he has a Cool area to escape to. If in the hot end the whole Viv will be the same heat. Not good.
> 
> A stat IS a safety feature, NOT a control device.
> 
> ...


Look up the meaning of thermo and stat. Of course it's a control device!

Which particular bit of my post is a "misconception"? I've explained exactly why the probe needs to be placed where it is and why the "safety feature" argument doesn't work properly.

I keep the stat "debate" going precisely because there is such widespread ignorance about temperature control mechanisms, heat transfer and temperature gradients. I don't care if 99% of people do something -if it's wrong, it's wrong!

Maybe, when I was studying heat transfer at University, my lecturer on the subject (Prof J.F. Richardson), had actually got it all wrong - and that we should have referred to a couple of caresheets written by Hades Dragons?


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## Jeffers3 (May 18, 2010)

On second thoughts, I've been down this route too many times before and there are not enough people willing or able to think about what's happening in their viv.

Do what you want - it doesn't affect me, after all....


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## Meko (Apr 29, 2007)

Jeffers3 said:


> temperature gradients. I don't care if 99% of people do something -if it's wrong, it's wrong!


it's wrong because you think it's wrong.

Go and have a look at your central heating thermostat, is it right next to the radiator? thought not.
If you want to compare vivs to ovens, lets go for it. The viv is an oven, where's the thermosat? inside it. so that's your oven theory out of the window. 

We're not talking about heat transfer but heating a small 'room'. You put the thermostat wherever it goes to get the right balance of heat and if that means you put the thermostat in the cool end so that you get the right basking spot temperature and the right cool end temperature.... then it goes in the cool end. If you can put it in the warm end and it holds your cool and and warm end temperatures - then great! but the aim is to provide the right temperatures throughout the viv without making it too warm for the inhabitant.


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## Jeffers3 (May 18, 2010)

Meko said:


> it's wrong because you think it's wrong.
> 
> Go and have a look at your central heating thermostat, is it right next to the radiator? thought not.
> If you want to compare vivs to ovens, lets go for it. The viv is an oven, where's the thermosat? inside it. so that's your oven theory out of the window.
> ...


Last post on this, as it is obviously too complicated for you....

The central heating thermostat is irrelevant to this argument for several reasons. Firstly, you are not trying to set up a thermal gradient in your room. Secondly, and most importantly, the heating method has a much slower response mechanism. Even when the thermostat switches off, the heat source continues to emit heat, because of the residual energy held in the water in the radiator. 

The thermostat in the oven analogy - of course you place the thermostat near to the heat source. That's my whole point! It's a control device. The further it is away from the heat source, the longer it takes to respond. I was trying to illustrate, with an extreme example, that if you place the thermostat a long way from the heat source, it won't work properly. Try to keep up....

"We're not talking about heat transfer but heating a small 'room'." This is possibly the most stupid thing you've written. How can you heat ANYTHING without heat transfer? The whole process of establishing a thermal gradient in a vivarium is controlled by how much heat you supply at one end and the heat losses (also heat transfer) along the length of the viv.

I totally agree with your last few sentences, by the way. This is exactly why I posted on here. Whichever way we set up a viv, unless we have control over the ambient temperature, the heat losses will change the rate of heat loss affected the gradient. Re-read my more detailed post, as I was merely trying to explain why the probe needs to be placed where it is.


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## Richg (May 25, 2010)

Txxl3/]!

Edit: was only reading thread and somehow managed to post that


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## TheGuvnor (Apr 26, 2013)

er....thanks *Jeffers* for your "_private message_". I'm not getting into an argument on here, OR private.

A dimming stat for the use as we use them is for safety. This may or may not be technically correct. But its how they are used in the Bearded Dragon community. And also why they only go up to 40c maximum on the actual dimming stat. For SAFETY.

Considering a dragons basking spot should be around 42c, makes the 40c maximum pointless if you use it in the hot end:bash:
But if it works for you, then so be it. Thats cool. And if anyone wishes to follow your technique, so be it. I, like you, are just advising as the OP asked.


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## Jeffers3 (May 18, 2010)

TheGuvnor said:


> er....thanks *Jeffers* for your "_private message_". I'm not getting into an argument on here, OR private.
> 
> A dimming stat for the use as we use them is for safety. This may or may not be technically correct. But its how they are used in the Bearded Dragon community. And also why they only go up to 40c maximum on the actual dimming stat. For SAFETY.
> 
> ...


That's not why they only go up to too low a temperature. It's because they are badly designed and people had to adapt the way they used them. This then became THE way to use them. As usual, this became doctrine and nobody is allowed to question it.

It was the same for many years with leopard geckos and UV light provision. Thankfully, most people now understand the importance of UV for these crepuscular lizards. You wouldn't believe the abuse I have had from people about this. 

By the way, I went private to continue our discussion away from a new posters thread. Never mind. I've said my bit. Maybe it's time to leave the "Flat Earth Society" to it! :lol2:


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## TheGuvnor (Apr 26, 2013)

You keep saying you not getting in to the debate again, yet you keep going on.

Anyways, ClemSnide. Hope all is working out for you. Keep us updated 

Sent from my GT-i9500 using Tapatalk 4 beta.


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## Jeffers3 (May 18, 2010)

TheGuvnor said:


> You keep saying you not getting in to the debate again, yet you keep going on.
> 
> Anyways, ClemSnide. Hope all is working out for you. Keep us updated
> 
> Sent from my GT-i9500 using Tapatalk 4 beta.


 
Occupational hazard as a lecturer, but you're right!:2thumb:

Ditto your second comment - with apologies!


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## TheGuvnor (Apr 26, 2013)

All good dude, all good 

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