UVB Light & Set-up concerns

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eisbrecher
Posts: 12
Joined: 27 May 2017, 10:24

UVB Light & Set-up concerns

Post by eisbrecher » 27 May 2017, 10:46

Good morning!

I have had my beloved Torkoal (horsefield tortoise) for maybe 8-9 months, I hear that mercury vapour bulbs can 'wear out' so even though they still work light-wise, they stop giving off as much UVB, is this the case?

I tend to get a mercury vapour bulb, more expensive than heat and UVB together but I am happy with them for ease of use and only needing a singe light fitting. https://www.reptiles.swelluk.com/reptil ... our-bulbs/
There are numerous wattages, I have no idea which one would be best for my tortoise based on the table set-up
He has a window which shines sunlight over the table for at least 5-7hours a day also, but does the window affect the UVB?

Heatwise, the table has a radiator on both sides, they are triggered to keep the temperature at least 18degrees at night and 26 degrees during the day, the temperature under the lamp is, I believe, around 28-30 (I have tried using a digital thermometer but it didnt work at all)
FYI the thermostat for the radiators happens to be about 8 feet from the tortoise table. I feel the heat is just fine for him right now, anyone disagree? Always looking for alternative ideas!

Many thanks!

(Credit where credit is due, I did not make the table, it is from petandtortoiseworld.co.uk, they were super accommodating, my table is double the size of their usual tables but they were happy to enlarge it for a very modest fee! Came in a flat-pack style box and super easy to put together, even for me!)

EDIT - I should of put this in the Enclosures sub-forum...apologies!
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Nina
Posts: 1119
Joined: 16 Mar 2017, 11:22

Re: UVB Light & Set-up concerns

Post by Nina » 27 May 2017, 11:28

Hi, and good morning to you too (and it's great to hear that Torkoal has such a lovely enclosure -- it looks super and you've decorated it nicely so that he has objects to walk over and around to keep his interest up.

Re the lighting. Yes, the bulbs do 'wear out' regarding UVB, even though the light still is emitted. What happens is that over time, the UVB causes a sort of coating to build up on the inside of the bulb (and this is true of the mercury vapour bulbs and the fluorescent uvb tubes), and this prevents the UVB from getting through, even though the light still gets through. So it is best to follow the manufacturer's instructions on how often to change the bulbs (I think it is every year or two, depending on how many hours the lamps are used).

Re your windows. UVB cannot pass through glass or most plastics, although there are particular acrylic materials that do allow UVB to pass through -- so Torkoal will be getting light and warmth through the windows but no UVB.

Regarding wattage. I think you just need a bulb that will produce the right temperature in the table, and I would think that something like a 100W bulb would be plenty for a table of that size -- maybe even slightly less if the temperature of the room is really warm. The ambient temperature of the room really does affect the temperature in the table, so it is good to have the facility to raise or lower the lamp to raise or lower the temperature.

Re night time -- the temperature can fall lower than 18C -- and in fact tortoises do like a bit of a drop in temperature at night -- and it can easily go down to 14C or 15C if you like.

Temperature. It is very important to measure the temperaturer directly below the heat source at the height of Torkoal's shell. A thermometer mounted on a nearby wall will give you a false -- and much lower -- reading. I use one of those digital fridge thermometers (the kind with a display unit and then a long wire with a probe on the end). I hang the probe down to as near as I can get it to under the lame. It's like one of these:
http://tinyurl.com/ya2ge23g and you can get them in lots of places. The Max/Min facility is useful too, so that you can see how high or low the temperature went since you last re-set it. LOL, I have a chopstick taped to the side of my table, protruding out into the table, and I wind the cord around that and then suspend it down at the right height under the lamp -- not very sophisticated, but it works (but you could easily suspend it from above).

Hope that helps,
Nina

eisbrecher
Posts: 12
Joined: 27 May 2017, 10:24

Re: UVB Light & Set-up concerns

Post by eisbrecher » 27 May 2017, 11:48

Many thanks,

I will obtain a (working, accurate) thermometer this time, The lamp can be moved up or down via removing and re-attaching via a screw (the connecting wooden piece has numerous holes in it so you can choose how high the lamp should be) Will hold back on buying a bulb until I get a thermometer. The one I have is 100W, if its not warm enough at top of shell level in basking area will upgrade to 125W and check with thermometer to make sure all is ok

I'll change the thermostat a bit, the bulb automatically turns off at 9:30, at that point he wanders upstairs into his little house to sleep. He can hear the tiny 'ping' noise of the bulb coming back on at 7:45 so he slowly makes his way down to the basking area

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Nina
Posts: 1119
Joined: 16 Mar 2017, 11:22

Re: UVB Light & Set-up concerns

Post by Nina » 27 May 2017, 14:08

Aww, how sweet that he goes up to his lttle bedroom each night (and of course he is getting good exercise walking up and down that ramp)!
If it's not warm enough in the table, you could try lowering the lamp an inch or two, and the temperature will definitely go up. I use a 90W bulb and it's fine -- but on a hot day (like the few we had recently) I did have to raise it up to lower the temperature in the table.

Nina

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