Thermostat when only source of heat is basking light

[adrigon88]

Hello all,

There are many posts about thermostats and heat soruces but still I am uncertain of what is the best for my setup.

My tortoise is a (roughly) 3 year old hermanni.

My terrarium (plastic cover + wooden enclosure) is in a heated room inside the house. The room temperature is always 20 °C or higher, up to 25-26 °C in hot days

That means that with the cover the only heat source I need is the basking light to keep all warm in the terrarium. In fact I am worrying that it will get too warm now that the summer approaches.

I read in several post that people normally do not connect a thermostat to the basking light they just adjust the height. However in my close terrarium the heat would build up anyway.

In this case is it the best to connect a dimable bulb with a thermostat/rehostat and put the sensor in the cold side? I am assuming I can find a tech solution that dims the basking light but does not switch it off. In this way I would not control automatically the basking light temprature but I would make sure that the tort has a cold side at an ok temperature.

What do you think? Is this plan OK?

Another option is to not cover the enclosure over summer but then humidity might be a problem.

Thanks in advance

 

[The_Four_Toed_Edward]

Hopefully @Alex and the Redfoot can advise you.

 

[Tom]

Hello all,

There are many posts about thermostats and heat soruces but still I am uncertain of what is the best for my setup.

My tortoise is a (roughly) 3 year old hermanni.

My terrarium (plastic cover + wooden enclosure) is in a heated room inside the house. The room temperature is always 20 °C or higher, up to 25-26 °C in hot days

That means that with the cover the only heat source I need is the basking light to keep all warm in the terrarium. In fact I am worrying that it will get too warm now that the summer approaches.

I read in several post that people normally do not connect a thermostat to the basking light they just adjust the height. However in my close terrarium the heat would build up anyway.

In this case is it the best to connect a dimable bulb with a thermostat/rehostat and put the sensor in the cold side? I am assuming I can find a tech solution that dims the basking light but does not switch it off. In this way I would not control automatically the basking light temprature but I would make sure that the tort has a cold side at an ok temperature.

What do you think? Is this plan OK?

Another option is to not cover the enclosure over summer but then humidity might be a problem.

Thanks in advance

If your bulb is overheating your enclosure at any time, then you need a lower wattage bulb. I use 65 watt bulbs in colder weather, 45 watt bulbs in spring and fall, and 25 watt bulbs in summer in my large closed chambers.

The basking lamp should be on a timer. You don't want to use a thermostat because then the sun would be going on and off all day. I saw someone with that set up and the bulb turned on and off about 10 times in the space of 40 minutes. That's no good. It drove me crazy from outside the enclosure. I can't imagine how the lizard in that enclosure must have felt.

Alternatively, you can run the bulb through both a timer and a rheostat. Use the rheostat to dial down the wattage as needed.

 

[Alex and the Redfoot]

You can use a lower wattage bulb as Tom said. It works better than dimmed high wattage bulb (because output spectrum and brightness are different).

However, as a safety measure, you can use a thermostat. For that purpose I would opt for on/off thermostats with adjustable temperature difference (hysteresis) - you can set e.g. 10F difference, so when bulb switches off, temperature has to drop for 10F before bulb is switched back on. Dimming thermostats can achieve similar results. This is complimentary to the usage of right wattage bulb, not an alternative.

At 3 years old your tortoise may be almost fully grown and high humidity is not required (but not harmful, though).

 

[Markw84]

I use a thermostat on all my closed chambers for overheat protection on the basking light. A good closed chamber holds heat (and humidity) extremely well, so a basking light, especially when A HO T5 UVb is on too, will overheat the enclosure.

As @Alex and the Redfoot mentions, I use a thermostat with an adjustable hysteresis. A thermostat without that would go on and off too frequently. I set mine to 4° hysteresis (differential) and usually have it set to about 94°. The basking thermostat is plugged into a timer and the basking light is plugged into the thermostat. It will go off when the temperature reaches 94° and then back on when the temperature falls to 90°. I place that thermostat probe about 6" above substrate and perhaps 6" off to the side of the basking area. In the summer on warmer days in the tortoise lab, it can cycle on and off every 40 minutes or so, but that's not much different than the sun going behind clouds on a normal day in the tropics.

I use this for all my tortoises - pancake, spider, manoria, Galapagos, Burmese Stars, radiated. I find it works very well for all them. 94° ambient is high enough for the tortoise to have all the body heat it needs, and the UVB is still providing a bright spot that attracts basking behavior even with the basking light off. You will find there is not much basking behavior in a tortoise when the ambient is 94°.

 

[adrigon88]

thanks for all the feedback

 

[GardiendeKoopa]

@Markw84 What basking light are you using? Just the basking light and a UV tube can overheat the enclosure? What size enclosures, just 4x3 or would one basking lamp also overheat an 8x3?