# Combi bulbs and pyramiding



## Hanami (Dec 6, 2020)

I'd like to know whether combi bulbs and the uvb (or lack there of) can contribute to pyramiding.
I know humidity, diet and other factors contribute but I'm in essence trying to find sourced information as to whether the combi bulbs are a reliable source of constant uvb.
Personally I use a T5 and separate basking light.
This is more for research purposes and preventative information for other tort keepers if it is indeed an issue as I can't seem to find the source to which Initially led me to this conclusion.


Thanks ☺


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## Tom (Dec 6, 2020)

If by "combi bulbs" you are referring to mercury vapor bulbs that produce heat and UV, then yes, they do cause pyramiding by overly desiccating the carapace.

Diet isn't a factor in pyramiding. Calcium and UV are not factors. That is old incorrect info. Artificial UV bulbs can contribute to pyramiding due to the high levels of UVA that they generate, which causes excessive carapace desiccation.

Your strategy of the basking bulb (hopefully a low wattage flood type) and the HO tube for UV, is the least damaging indoor housing strategy right now. Adding ambient heat during the day, will also encourage less basking, and reduce the damage done by our desiccating indoor bulbs. Likewise, I prefer to have strong UV from the tubes and only run them on a timer from 1-3 hours mid day. This somewhat simulates the strong mid day UV spike outside, vs a lower level UV bulb that rinse all day.


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## Hanami (Dec 6, 2020)

Thanks Tom,
I appreciate the information, it's a shame I have outdated information though ?
If you get chance to maybe link a source for me regarding the mercury vapour bulbs that would be great.
I've searched but I'm obviously looking in the wrong places.

Thanks


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## Tom (Dec 6, 2020)

Hanami said:


> Thanks Tom,
> I appreciate the information, it's a shame I have outdated information though ?
> If you get chance to maybe link a source for me regarding the mercury vapour bulbs that would be great.
> I've searched but I'm obviously looking in the wrong places.
> ...


The source for the new information regarding MVBs causing pyramiding is: Tortoiseforum.org


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