Thermostat query

Questions about designing a terrarium.
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StarJohn
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Thermostat query

Post by StarJohn »

Hello
I am currently using a UTH mounted on the back wall covering one half of the tank - half below substrate and half above. This is attached to a thermostat with the probe hanging two thirds of the way down the tank on the warm side. To achieve the correct air temperature inside the tank I am finding I have to have the thermostat set around 7 or 8° higher than the temperature I want the tank at. Does anyone else find they have to do this or is there something wrong with my thermostat? I am using a digital thermometer with the probe hanging next to the thermostat probe.
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appps
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Re: Thermostat query

Post by appps »

My thermostats are all a couple degrees off, not that many though. I calibrated my thermometer so I just do what you have and set them to slightly higher than I want so they maintain correctly according to the thermometer.
Annette
Carer of 5 Australian Land Hermit Crabs
Fili & Voldemort since 12/07/2011
Turbo since 29/09/2011
Frederickson & Kai 12/02/2012
and our new addition Stripey Ninja 25/10/2014

Our Crab tank setup & Journal -http://crabbycreatures.wordpress.com
StarJohn
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Re: Thermostat query

Post by StarJohn »

Ok thanks as always appps! Forgive me if this question sounds silly but is there any way to calibrate a digital thermometer or is that only for analog?
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emmac350
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Re: Thermostat query

Post by emmac350 »

Air temperature is much less important than substrate temperature, especially if your thermostat probe is in the air. Air temperature is in and of itself highly variable (and easily changeable) - it loses heat extremely quickly, as opposed to your substrate which will be much more stable. If you're using a UTH to try to change air temperature you are probably heating way more than you should, which could result in your UTH over-heating your substrate and being dangerous to your crabs.
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appps
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Re: Thermostat query

Post by appps »

I'm a little bit on the outer as far as that goes, I ignore the substrate temperature totally and only measure the air.

My logic is that it is the air temp in the wild that we know and so should be recreating. The substrate just needs to be cooler so they can burrow if they need to to cool down. I've never seen any data showing the substrate temperature in the wild for us to copy. I do know I'm in the minority though :-)

Of course if using un uth you need to monitor it so you don't cook them.
Annette
Carer of 5 Australian Land Hermit Crabs
Fili & Voldemort since 12/07/2011
Turbo since 29/09/2011
Frederickson & Kai 12/02/2012
and our new addition Stripey Ninja 25/10/2014

Our Crab tank setup & Journal -http://crabbycreatures.wordpress.com
StarJohn
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Re: Thermostat query

Post by StarJohn »

Thanks everyone. This is all a bit of a learning curve for me at the moment. My substrate definitely feels quite cool (cooler than the air). I have filled a trench with large flat rocks along the glass where the UTH is positioned under the substrate so they can't get down along that area. There is nothing protecting the glass above ground where UTH is however I figure if it's too hot there they will just move away (and so far they have spent a lot of time sitting next to it).
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emmac350
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Re: Thermostat query

Post by emmac350 »

The ground outside actually maintains a fairly even range of temperatures all year round. So in the summer, it feels cool to us because the air is so warm. In the winter, dig down beyond the surface and it'll actually be warm. It's the idea behind geothermally heated homes - homes built into caves or hillsides. Your house will be the same temperature all year round. So I prefer to keep an even substrate temperature because the inside of my house changes air temperature a lot during the seasons (and not the way that seems SUPER popular here - to cool it to 70 in the summer and heat it to 80 in the winter...but still wear seasonally appropriate clothes...I really don't understand Korea sometimes!). That might not make much sense...sorry.

Though I am confused, StarJohn - if your UTH under the substrate doesn't actually *touch* your substrate, how would it heat the substrate at all? If you purposely put half the heater under substrate level, I'm not sure how that makes sense. Just trying to understand!

Happy Friday all!
Follow the daily lives of my crabs at thedailyhermit.tumblr.com

Mommy to:
Rack, 23 Sep 08; Benny, 23 Sep 08; Slightly, 3 Jan 09; Nibs, 3 Jan 09; Curly, 3 Jan 09; Spaz, 5 Jul 09

If you are contacted privately and enticed to join another forum, please inform a moderator. This is an unethical practice.
StarJohn
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Joined: 17 Jan 2015, 16:08
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Re: Thermostat query

Post by StarJohn »

Sorry for delay in reply Emmac350. I put the rocks alongside the UTH based on advice from this forum. The theory being that I might cook the crabs if they bury down alongside the glass where it is positioned. My reasoning for putting in half above substrate and half below was that I hoped it would boost temperatures in both areas. I am now monitoring temperatures in both the air and the substrate but am having quite a lot of trouble! I have just posted another post entitled " desperate heating help needed ". Any advice would be greatly appreciated. Thanks for all the help!!!!!!
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