Infrared - sunlight vs. basking lamps

gtc

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Jan 6, 2013
Messages
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mikeh said:
gtc said:
mikeh said:
gtc, yes, you got idea.....
Ideally you want to create same basking temperature as with regular basking lights. I would go with 95F for arid species. Because the heat output of T5HO is not as intense the height to create this basking temp will depend on weather you have closed chamber and size or open table and room temperature. It could be anything from 10"-18", that will also determine strength and number of UVB tubes.
If you provide some details I can give you better idea on tubes.

Thank you,

The attached photo is not current, I have covered about 90-95% of the top now in order to keep humidity at basking zone between 25-30% and 60-70% in rest of enclosure. I use a 160W powersun mvb now.

Due to the climate my greek lives about 9 months indoors and always sleeps indoors.

I am considering changing to your setup after reading all these interesting posts, especially when in about 2 years I plan to make a very large indoor enclosure and I wish to have large basking zones.

My biggest concern is if uvb tubes (compared to mvb) can provide enough uvb for adequate vit D synthesis in torts that dont get a lot outside time. Also since the future indoor enclosure will be open and about 3 yards by 6 yards I wonder if the tubes will be able to produce a hot enough basking temp?

On your biggest concern of UVB: T5HO UVB tubes are superior to MVBs. They mimic suns spectrum better then MVBs and last much longer. MVBs (Mega Ray may be the exception) are known to fail within as little as one month, rendering them useless for UVB. T5HO Arcadia D3+ are good for up to one year. In short T5HO tubes are better choice for UVB.

For your current set up 24" T5HO quad fixture seems ideal. Fixture placed in the middle with most of the enclosure covered as you have now. This would increase your basking area humidity to 45%-55% with rest remaining at your current levels.
Here is link to a hydrofarm fixture.

http://www.megagrowers.com/t5-designer-2ft-4-tube-fixture-w-bulbs/?gclid=CMaXx66c77sCFYtQOgodGDIAjQ

It comes with grow lights. This will allow you to determine at what height you will set the fixture to obtain desired basking temp. The ideal height will then determine what strength UVB tube(s) are appropriate.

Heights 10"-12" will yield lover UVB tubes such as Zoomed 5% or Arcadia D3+ 6%.
Height of 15-18" will yeild higher UVB tubes, Zoomed 10% or Arcadia D3+12%.
Either set up with two uvb tubes placed in the outer positions of the fixture seem ideal, with grow lights on the inside positions.

For your future 3yards by 6yards enclosure you would need 4' 6-8tube fixture or maybe even creating two basking areas with two large fixtures.

___________________________________

If your tortoise spends hours on end under the MVB you have, it is having a drying effect on its carapace not only by lowering humidity to very low levels under the bulb but also by IRA spectrum the heat bulbs produce. It is suggested this may be one of the factors contributing to pyramiding, that's what this thread is about.

Since T5HO lights don't dry out the humidity it would seem they don't produce as high of IRA spectrum thus not having this negative effect on the shell, although testing is needed. Hopefully one of our members will test them with rest of the heat lights in next couple of months to give us better answers.

First of all, thank you for the great info. I found a place in my country that sells the exact same fixture you recommended (it costs 300 dollars here though).

Its funny, I went for a mvb + ceramic base with dome + zoomed light stand (which I paid over 600 dollars for here, everything is so cheap in the USA :p ) since I read that mvb's produced a better spectrum that T5 tubes. My last powersun lasted for the full 9 months I used it, and I just bought a new one a month ago. Do you think that pyramiding is possible even if I go from 90% cover to 100% cover and increase the humidity to maybe 35-40% under the bulb? If so I will go ahead that buy the new setup right away. Otherwise I am considering waiting 9 more months and when the time comes to replace my mvb to switch to your setup. The most important thing the the well being of my tortoise.
 

mikeh

Well-Known Member
5 Year Member
Joined
Jun 16, 2013
Messages
1,050
Re: RE: Infrared - sunlight vs. basking lamps

gtc said:
mikeh said:
gtc said:
mikeh said:
gtc, yes, you got idea.....
Ideally you want to create same basking temperature as with regular basking lights. I would go with 95F for arid species. Because the heat output of T5HO is not as intense the height to create this basking temp will depend on weather you have closed chamber and size or open table and room temperature. It could be anything from 10"-18", that will also determine strength and number of UVB tubes.
If you provide some details I can give you better idea on tubes.

Thank you,

The attached photo is not current, I have covered about 90-95% of the top now in order to keep humidity at basking zone between 25-30% and 60-70% in rest of enclosure. I use a 160W powersun mvb now.

Due to the climate my greek lives about 9 months indoors and always sleeps indoors.

I am considering changing to your setup after reading all these interesting posts, especially when in about 2 years I plan to make a very large indoor enclosure and I wish to have large basking zones.

My biggest concern is if uvb tubes (compared to mvb) can provide enough uvb for adequate vit D synthesis in torts that dont get a lot outside time. Also since the future indoor enclosure will be open and about 3 yards by 6 yards I wonder if the tubes will be able to produce a hot enough basking temp?

On your biggest concern of UVB: T5HO UVB tubes are superior to MVBs. They mimic suns spectrum better then MVBs and last much longer. MVBs (Mega Ray may be the exception) are known to fail within as little as one month, rendering them useless for UVB. T5HO Arcadia D3+ are good for up to one year. In short T5HO tubes are better choice for UVB.

For your current set up 24" T5HO quad fixture seems ideal. Fixture placed in the middle with most of the enclosure covered as you have now. This would increase your basking area humidity to 45%-55% with rest remaining at your current levels.
Here is link to a hydrofarm fixture.

http://www.megagrowers.com/t5-designer-2ft-4-tube-fixture-w-bulbs/?gclid=CMaXx66c77sCFYtQOgodGDIAjQ

It comes with grow lights. This will allow you to determine at what height you will set the fixture to obtain desired basking temp. The ideal height will then determine what strength UVB tube(s) are appropriate.

Heights 10"-12" will yield lover UVB tubes such as Zoomed 5% or Arcadia D3+ 6%.
Height of 15-18" will yeild higher UVB tubes, Zoomed 10% or Arcadia D3+12%.
Either set up with two uvb tubes placed in the outer positions of the fixture seem ideal, with grow lights on the inside positions.

For your future 3yards by 6yards enclosure you would need 4' 6-8tube fixture or maybe even creating two basking areas with two large fixtures.

___________________________________

If your tortoise spends hours on end under the MVB you have, it is having a drying effect on its carapace not only by lowering humidity to very low levels under the bulb but also by IRA spectrum the heat bulbs produce. It is suggested this may be one of the factors contributing to pyramiding, that's what this thread is about.

Since T5HO lights don't dry out the humidity it would seem they don't produce as high of IRA spectrum thus not having this negative effect on the shell, although testing is needed. Hopefully one of our members will test them with rest of the heat lights in next couple of months to give us better answers.

First of all, thank you for the great info. I found a place in my country that sells the exact same fixture you recommended (it costs 300 dollars here though).

Its funny, I went for a mvb + ceramic base with dome + zoomed light stand (which I paid over 600 dollars for here, everything is so cheap in the USA :p ) since I read that mvb's produced a better spectrum that T5 tubes. My last powersun lasted for the full 9 months I used it, and I just bought a new one a month ago. Do you think that pyramiding is possible even if I go from 90% cover to 100% cover and increase the humidity to maybe 35-40% under the bulb? If so I will go ahead that buy the new setup right away. Otherwise I am considering waiting 9 more months and when the time comes to replace my mvb to switch to your setup. The most important thing the the well being of my tortoise.

Just because MVB lights up doesn't mean it is producing UVB. Unless you measured it with UVB meter there is no way of knowing. I seriously doubt power sun would produce UVB at 9 or even 6 months.

I am not sure where you read MVB produces better UVB spectrum then T5HO, but that sounds like marketing nonsense. Independent tests tell a very different picture.



Since things are so expensive in Norway and you have a new MVB, chances are you are OK for next two or so months. I would attempt to increase the humidity under the light without effecting humidity in rest of the enclosure, which seems ideal as you have it. This may involve misting the substrate just under the light couple times a day. Misting the tortoise may also help. But its not just the very low humidity under the bulb, its also the IRA the bulb produces.

You have had the tortoise now for many months, if its growing smooth, shell is hard , along with balanced nutrition chances are things are going well for him/her in your set up.

When the time comes in next couple months to replace the MVB, you can then decide to switch to T5HO. One other factor is day time room temperature the tortoise table is in. Since T5HO lights are not as intense, they may not create sufficient heat in room of ambient temp. below 70F.
 

gtc

Member
5 Year Member
Joined
Jan 6, 2013
Messages
265
Location (City and/or State)
Norway
mikeh said:
gtc said:
mikeh said:
gtc said:
mikeh said:
gtc, yes, you got idea.....
Ideally you want to create same basking temperature as with regular basking lights. I would go with 95F for arid species. Because the heat output of T5HO is not as intense the height to create this basking temp will depend on weather you have closed chamber and size or open table and room temperature. It could be anything from 10"-18", that will also determine strength and number of UVB tubes.
If you provide some details I can give you better idea on tubes.

Thank you,

The attached photo is not current, I have covered about 90-95% of the top now in order to keep humidity at basking zone between 25-30% and 60-70% in rest of enclosure. I use a 160W powersun mvb now.

Due to the climate my greek lives about 9 months indoors and always sleeps indoors.

I am considering changing to your setup after reading all these interesting posts, especially when in about 2 years I plan to make a very large indoor enclosure and I wish to have large basking zones.

My biggest concern is if uvb tubes (compared to mvb) can provide enough uvb for adequate vit D synthesis in torts that dont get a lot outside time. Also since the future indoor enclosure will be open and about 3 yards by 6 yards I wonder if the tubes will be able to produce a hot enough basking temp?

On your biggest concern of UVB: T5HO UVB tubes are superior to MVBs. They mimic suns spectrum better then MVBs and last much longer. MVBs (Mega Ray may be the exception) are known to fail within as little as one month, rendering them useless for UVB. T5HO Arcadia D3+ are good for up to one year. In short T5HO tubes are better choice for UVB.

For your current set up 24" T5HO quad fixture seems ideal. Fixture placed in the middle with most of the enclosure covered as you have now. This would increase your basking area humidity to 45%-55% with rest remaining at your current levels.
Here is link to a hydrofarm fixture.

http://www.megagrowers.com/t5-designer-2ft-4-tube-fixture-w-bulbs/?gclid=CMaXx66c77sCFYtQOgodGDIAjQ

It comes with grow lights. This will allow you to determine at what height you will set the fixture to obtain desired basking temp. The ideal height will then determine what strength UVB tube(s) are appropriate.

Heights 10"-12" will yield lover UVB tubes such as Zoomed 5% or Arcadia D3+ 6%.
Height of 15-18" will yeild higher UVB tubes, Zoomed 10% or Arcadia D3+12%.
Either set up with two uvb tubes placed in the outer positions of the fixture seem ideal, with grow lights on the inside positions.

For your future 3yards by 6yards enclosure you would need 4' 6-8tube fixture or maybe even creating two basking areas with two large fixtures.

___________________________________

If your tortoise spends hours on end under the MVB you have, it is having a drying effect on its carapace not only by lowering humidity to very low levels under the bulb but also by IRA spectrum the heat bulbs produce. It is suggested this may be one of the factors contributing to pyramiding, that's what this thread is about.

Since T5HO lights don't dry out the humidity it would seem they don't produce as high of IRA spectrum thus not having this negative effect on the shell, although testing is needed. Hopefully one of our members will test them with rest of the heat lights in next couple of months to give us better answers.

First of all, thank you for the great info. I found a place in my country that sells the exact same fixture you recommended (it costs 300 dollars here though).

Its funny, I went for a mvb + ceramic base with dome + zoomed light stand (which I paid over 600 dollars for here, everything is so cheap in the USA :p ) since I read that mvb's produced a better spectrum that T5 tubes. My last powersun lasted for the full 9 months I used it, and I just bought a new one a month ago. Do you think that pyramiding is possible even if I go from 90% cover to 100% cover and increase the humidity to maybe 35-40% under the bulb? If so I will go ahead that buy the new setup right away. Otherwise I am considering waiting 9 more months and when the time comes to replace my mvb to switch to your setup. The most important thing the the well being of my tortoise.

Just because MVB lights up doesn't mean it is producing UVB. Unless you measured it with UVB meter there is no way of knowing. I seriously doubt power sun would produce UVB at 9 or even 6 months.

I am not sure where you read MVB produces better UVB spectrum then T5HO, but that sounds like marketing nonsense. Independent tests tell a very different picture.



Since things are so expensive in Norway and you have a new MVB, chances are you are OK for next two or so months. I would attempt to increase the humidity under the light without effecting humidity in rest of the enclosure, which seems ideal as you have it. This may involve misting the substrate just under the light couple times a day. Misting the tortoise may also help. But its not just the very low humidity under the bulb, its also the IRA the bulb produces.

You have had the tortoise now for many months, if its growing smooth, shell is hard , along with balanced nutrition chances are things are going well for him/her in your set up.

When the time comes in next couple months to replace the MVB, you can then decide to switch to T5HO. One other factor is day time room temperature the tortoise table is in. Since T5HO lights are not as intense, they may not create sufficient heat in room of ambient temp. below 70F.

Sounds like a good plan. I'll post pics of my new setup and the temps\humidity I get once I get it up and running :)
 

gtc

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Joined
Jan 6, 2013
Messages
265
Location (City and/or State)
Norway
Hi Mike,

I have been seriously looking into trying the new setup you tested. I am planing to get the 6% tubes because I think I will need to get the tubes quite low in order to get a basking temp of 95 F.

Before I start buying the fixture and tubes I have 2 questions:

1. I have read in a forum that someone with a solarmeter tested the arcadia T5 tubes and found that they produced too much UVB and had to put a mesh screen between the tube and the tort to lower the output. I am wondering if you have a solarmeter and if you have tested the output of the tube with the fixture you recommended with 1 arcadia 6% bulb vs 2 6% bulbs. I wonder if 2 might give too much uvb?

2. Have you started using this setup for any of your tortoises or are you still using the tubes with heaters + fan?
 

mikeh

Well-Known Member
5 Year Member
Joined
Jun 16, 2013
Messages
1,050
Re: RE: Infrared - sunlight vs. basking lamps

gtc said:
Hi Mike,

I have been seriously looking into trying the new setup you tested. I am planing to get the 6% tubes because I think I will need to get the tubes quite low in order to get a basking temp of 95 F.

Before I start buying the fixture and tubes I have 2 questions:

1. I have read in a forum that someone with a solarmeter tested the arcadia T5 tubes and found that they produced too much UVB and had to put a mesh screen between the tube and the tort to lower the output. I am wondering if you have a solarmeter and if you have tested the output of the tube with the fixture you recommended with 1 arcadia 6% bulb vs 2 6% bulbs. I wonder if 2 might give too much uvb?

2. Have you started using this setup for any of your tortoises or are you still using the tubes with heaters + fan?

I have not tested the bulbs with UVB meter, I don't currently have one. Arcadia website has charts of UVB output levels for different UVB tubes at different heights under each product to guide you.

I only have 12% tubes, even though I haven't measured , fresh out of the box the tubes do indeed have very high UVB/UVA output. At the initial power up, handling the powered fixture with my hands I could slightly smell my skin having the same scent as when melanin in the skin oxidizes under intense UVA/UVB in tanning beds.
As a precautionary measure I always let the Arcadia tubes burn in for 100 hours prior to use. The "access" output is lost during this burn in period, after which the output stabilizes at somewhat lower levels.

You can surely start with one 6% UVB tube. Adding additional tubes if needed later will increase UVB. (Frances pointed out earlier that in London Zoo the UVB set up for adult Aldabra tortoises consisting of multiple 4 foot, 6tube fixtures (equipped with all Arcadia 3D+ 12% tubes) is positioned 7 feet up of the ground for ideal UVB levels. This gives a rough picture of how clustering the UVB tubes increases levels.
You can also observe how your tortoise utilizes the fixture. If he spends significant amount of day under then one tube could be just fine, if less time perhaps two tubes to slightly increase area and uvb output to compensate. What's ideal?...I simply do not know, I don't think anyone has come up with a set protocol. I would read up as much as I can on your torts species and their natural habitat, to get some picture of how much UVB, what levels and hours of day on average is received in nature at your torts age, then try to replicate it based on torts behavior inside. But generally speaking arid tortoises housed indoors are UVB deprived receiving much less UVB then outdoor tortoises.

My current set up for 8month leopard consists of 4'x2'x20" fully closed chamber (glass on 3sides), 48"T5HO 2tube fixture. One Arcadia 12% UVB and one none UVB tube. The height changes with terrain under the fixture from 14-17". There is a 80watt supplemental heat cable that also serves as night heat, fan is primarily used to create HOT days. The heat cable is on thermostat to pick up any slack. As the room temperature is always at 62-64F these days, the cable does cycle on good amount. (I used the 2bulb 4' fixture fixture because it was on hand, if I was doing the set up from scratch I would have chosen 4bulb 2'fixture.)
The tort spends 6-8 hours a day in the vicinity of the fixture. I am going to purely speculate here, but my guess is with this set up ( how much time he spends under UVB/UVA) he is receiving amounts of ideal to higher levels. Any new bright white growth gets darker tan within few days, lots of his older growth is still changing from tan to black and good amount of his new growth is coming in black as well. I believe this darkening could be related to UVB/UVA exposure in leopards. His skin color especially on the top of his head has gotten darker, his front feet as well. His shell is very solid, with a slight give only at the new growth on the plastron. No vit D3 is supplemented. He has been strictly indoors since end of august. He is active all day with ravenous appetite on cool days and more relaxed on HOT days spending hours on end basking and not fixated on food as much.

Hope all these details help to some extent. You will have to play with the set up to get it where you want it, for me that's fun part of it. It will also reveal lots about behaviors, preferences and habits of your tort.
 

gtc

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Jan 6, 2013
Messages
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Update and preliminary test results:

My 4 x T5 tube fixture arrived! It only contains the growing tubes that came with it so far....been on for 1 hour at 10 inches above substrate level and the temps (analog and digital thermometer) both show 92 F. Ambient room temp was 73 F. Humidity dropped from 35 % to 26% right under the lamp and its keeping at 75 F and 52 % in the rest of the enclosure.

Its late so my greek didn't bother waking and coming out of his hide during testing.

So......not totally sure how I feel about these test results yet.

(possibly) negative aspects:10 inches is kind of close and 92 F kind of low.....

2 BIG questions:

1. is 92 F a warm enough basking area for a greek tortoise?

2. I would really like to use 2 arcadia T5 6% tubes in the fixture, but is 10 inches from substrate (even closer then from top of shell) too close??


From arcadia web site:

Arcadia T5 – 16mm D3 6% lamp and reflector

10cms (4 inches) 289uw/cm2
20cms. (7.8 inches) 145uw/cm2
30cms. (12 inches) 83uw/cm2
40cms. (15.7 inches) 56uw/cm2
 

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mikeh

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5 Year Member
Joined
Jun 16, 2013
Messages
1,050
Re: RE: Infrared - sunlight vs. basking lamps

gtc said:
Update and preliminary test results:

My 4 x T5 tube fixture arrived! It only contains the growing tubes that came with it so far....been on for 1 hour at 10 inches above substrate level and the temps (analog and digital thermometer) both show 92 F. Ambient room temp was 73 F. Humidity dropped from 35 % to 26% right under the lamp and its keeping at 75 F and 52 % in the rest of the enclosure.

Its late so my greek didn't bother waking and coming out of his hide during testing.

So......not totally sure how I feel about these test results yet.

(possibly) negative aspects:10 inches is kind of close and 92 F kind of low.....

2 BIG questions:

1. is 92 F a warm enough basking area for a greek tortoise?

2. I would really like to use 2 arcadia T5 6% tubes in the fixture, but is 10 inches from substrate (even closer then from top of shell) too close??


From arcadia web site:

Arcadia T5 – 16mm D3 6% lamp and reflector

10cms (4 inches) 289uw/cm2
20cms. (7.8 inches) 145uw/cm2
30cms. (12 inches) 83uw/cm2
40cms. (15.7 inches) 56uw/cm2

To further raise the temperature by couple degrees place very dark colored flat piece of slate rock under the light, size of about 1x1 foot. The rock will absorb the heat and then radiate it out. (Dark tile may work as well). Tortoises are very sensitive to heat and will easily find the warmest spot on top of the rock if it desires. You can also place couple plants just outside of the edge of the fixture helping in keeping the localized heat in the area. Further you can close the gap opening around the sides of the fixture. With these combinations you should be able to bring the temp. up to at least 95. If you wish to raise the humidity slightly under the lamp, mist the substrate with water just directly under the lamp every other day or as needed.

The distance of 10" with Arcadia D3+ 6% actually looks ideal. Below is a post from Frances from another thread. She is an expert on UVB. It explains the conversion of the artificial UVB to match outdoor UV index. In your case at 10" it translates to UV index 3-4 which is equivalent to earlier morning sun in the tropics. According to Arcadia chart at 10" it produces +/-120 microwats. 120:31.4 as per Frances formula gives UV index equivalent to 3.81 outdoors. Not too high at all.

Frances post on UV conversions:

This is going to be a long post. But I honestly don't know any really simple way of explaining this, so I'm going to work through it as carefully as I can, although I know it's a :tort::tort::tort: sort of thing to do to anyone so late at night... 



Yes.  You will get a very good idea of how the UVB changes with time of day and with the seasons - and find the best places for your tortoises to sun-bask.




This is where the problem is, I'm afraid.

The Solarmeter 6.2 is designed to read the whole UVB spectrum. This includes shorter wavelengths, which are very effective at creating vitamin D, and longer wavelengths which have a less powerful effect. Sunlight has a lot of these longer wavelengths, which contribute a great deal to the reading on a Solarmeter 6.2.

But Reptile lamps almost all have a different spectrum from sunlight.
Some have a spectrum that is fairly similar - like most metal halide lamps and fluorescent tubes. Usually these have UVB spectra rather similar to strong tropical midday sunlight - powerful, but fine if positioned at the right distance.
Others, like many of the mercury vapour tubes and a few fluorescent tubes, have a much greater proportion of their UVB in the shorter, more reactive wavelengths. A small amount of this can have as powerful an effect on the skin as a large amount of longer-wavelength UVB.

But the Solarmeter 6.2 can't distinguish between "shorter wavelength" and "longer wavelength" UVB. It just gives you a Total UVB reading.
So... for some tubes and quite a few mercury vapour lamps, you don't want to match "full sunlight" values, with a Solarmeter 6.2 reading, because although (for example) 300 µW/cm² of sunlight is typical of sunlight at about 9.30 - 10.00am in the tropics, and safe enough.... 300 µW/cm² of UVB from some lamps would contain far too much shorter-wavelength UVB, and could even be hazardous for delicate eyes and skin.

The Solarmeter 6.5 is designed to respond more strongly to the shorter wavelength UVB (by a filter selectively reducing the longer wavelength UVB that reaches the sensor) its readings from lamps and from the sun are much better correlated.
So it is possible to "match" lamp and sunlight readings and be fairly certain that with a good quality lamp, the UV Index you are reading at the tortoise's basking level isn't far off the same "strength" as sunlight giving you the same reading.

Lots of people have asked me if there's a simple formula for converting a UVB reading (µW/cm²) from a 6.2 meter into a UV Index reading.
I wish there was! But because each brand of lamp has a slightly different spectrum, and "new improved" products will doubtless have new spectra too, it's an everlasting game. The only way to do it is to take sets of readings from a lamp, at the same distance, from both meters and plot a graph, from which you can get what's known as a regression formula... (a conversion formula).
Here are some samples, i.e., conversion formulas I've worked out for some lamps I've tested in the last three or four years, using my pair of Solarmeters. You're welcome to use these formulae but please bear in mind that there's no way I can be certain that your lamps are exactly the same as mine; and I only did the calculation on a tiny sample of lamps. So it's not really more than an estimate... (If anyone has 2 meters and some lamps, and wants to set to work plotting some more... please do!  )

So: To get the approximate UV Index from a Solarmeter 6.2 reading, divide the Solarmeter 6.2 reading by the following numbers:

For a ZooMed Reptisun 5.0 or an Arcadia D3 6%UVB tube: 31.4 (average calculated from 4 lamps)
For a ZooMed Reptisun 10.0 or an Arcadia D3+ 12%UVB tube: 32.7 (average calculated from 14 lamps)
For a 100watt ZooMed Powersun : 12.2 (average calculated from 5 lamps)
For a 125watt ExoTerra Solar Glo: 19.4 (average calculated from 3 lamps)
For a 160watt ExoTerra Solar Glo: 16.7 (average calculated from 2 lamps)
For an ExoTerra SunRay Metal Halide lamp: 36.6 (average calculated from 2 lamps, one 50W and one 70W)

To find out what the approximate Solarmeter 6.2 reading would be, at a specific UV Index, multiply the numbers by the UV Index you need.
e.g. if you want a UV Index of 2 under a ZooMed Reptisun 5.0 tube, multiply 31.4 by 2.
So UVI 2 would read about 63 µW/cm² under a ZooMed Reptisun 5.0 tube....
.....ok?

For the sun, it's really complicated because it changes depending on the height of the sun in the sky. My formula requires a calculator!
But here are some calculations I made based on a large number of paired solar readings plotted on a graph...
UVI 1 = 57µW/cm²
UVI 2 = 108µW/cm²
UVI 3 = 155µW/cm²
UVI 7 = 301µW/cm²
UVI 12 = 437µW/cm²
UVI 15 = 521µW/cm²

For example.... suppose I wanted to create a basking zone with a maximum UVI of 3. This is like early morning sunshine about 8.30am in the tropics.
If I was measuring sunlight the Solarmeter 6.2 might read about 150 µW/cm².
To match that, I would need approximately:
98 µW/cm² with a ZooMed Reptisun 10.0 (3 x 32.7)
37 µW/cm² with a 100watt ZooMed Powersun (3 x 12.2)

Does this make sense to anyone or have you all lost the will to live 




Yes, this is what the Solarmeter 6.2 excels in. Take measurements always at the same distance from the lamp, about once a month and you will be able to see how the UVB gradually declines with age.
In the first month, most lamps lose quite a lot, but after that the output from a good quality lamp of most types remains quite good for about a full year, only declining quite slowly... It's usual to replace a lamp when it's lost 50% of the UVB it had at first. With some types, e.g., ones that don't put out a lot of heat, you can keep the basking zone UVB the same over the year by lowering the lamp a little, as necessary, as its output falls.
By taking monthly readings you may discover that some good quality bulbs will keep going for well over a year, without needing changing.
Or when they are getting a bit low for a sun-basking species, you can use them over a shade-dweller - people can sometimes get 2 or even 3 years of life out of a good lamp in this way.

Best wishes,
Frances
 

gtc

Member
5 Year Member
Joined
Jan 6, 2013
Messages
265
Location (City and/or State)
Norway
mikeh said:
gtc said:
Update and preliminary test results:

My 4 x T5 tube fixture arrived! It only contains the growing tubes that came with it so far....been on for 1 hour at 10 inches above substrate level and the temps (analog and digital thermometer) both show 92 F. Ambient room temp was 73 F. Humidity dropped from 35 % to 26% right under the lamp and its keeping at 75 F and 52 % in the rest of the enclosure.

Its late so my greek didn't bother waking and coming out of his hide during testing.

So......not totally sure how I feel about these test results yet.

(possibly) negative aspects:10 inches is kind of close and 92 F kind of low.....

2 BIG questions:

1. is 92 F a warm enough basking area for a greek tortoise?

2. I would really like to use 2 arcadia T5 6% tubes in the fixture, but is 10 inches from substrate (even closer then from top of shell) too close??


From arcadia web site:

Arcadia T5 – 16mm D3 6% lamp and reflector

10cms (4 inches) 289uw/cm2
20cms. (7.8 inches) 145uw/cm2
30cms. (12 inches) 83uw/cm2
40cms. (15.7 inches) 56uw/cm2

To further raise the temperature by couple degrees place very dark colored flat piece of slate rock under the light, size of about 1x1 foot. The rock will absorb the heat and then radiate it out. (Dark tile may work as well). Tortoises are very sensitive to heat and will easily find the warmest spot on top of the rock if it desires. You can also place couple plants just outside of the edge of the fixture helping in keeping the localized heat in the area. Further you can close the gap opening around the sides of the fixture. With these combinations you should be able to bring the temp. up to at least 95. If you wish to raise the humidity slightly under the lamp, mist the substrate with water just directly under the lamp every other day or as needed.

The distance of 10" with Arcadia D3+ 6% actually looks ideal. Below is a post from Frances from another thread. She is an expert on UVB. It explains the conversion of the artificial UVB to match outdoor UV index. In your case at 10" it translates to UV index 3-4 which is equivalent to earlier morning sun in the tropics. According to Arcadia chart at 10" it produces +/-120 microwats. 120:31.4 as per Frances formula gives UV index equivalent to 3.81 outdoors. Not too high at all.

Frances post on UV conversions:

This is going to be a long post. But I honestly don't know any really simple way of explaining this, so I'm going to work through it as carefully as I can, although I know it's a :tort::tort::tort: sort of thing to do to anyone so late at night... 



Yes.  You will get a very good idea of how the UVB changes with time of day and with the seasons - and find the best places for your tortoises to sun-bask.




This is where the problem is, I'm afraid.

The Solarmeter 6.2 is designed to read the whole UVB spectrum. This includes shorter wavelengths, which are very effective at creating vitamin D, and longer wavelengths which have a less powerful effect. Sunlight has a lot of these longer wavelengths, which contribute a great deal to the reading on a Solarmeter 6.2.

But Reptile lamps almost all have a different spectrum from sunlight.
Some have a spectrum that is fairly similar - like most metal halide lamps and fluorescent tubes. Usually these have UVB spectra rather similar to strong tropical midday sunlight - powerful, but fine if positioned at the right distance.
Others, like many of the mercury vapour tubes and a few fluorescent tubes, have a much greater proportion of their UVB in the shorter, more reactive wavelengths. A small amount of this can have as powerful an effect on the skin as a large amount of longer-wavelength UVB.

But the Solarmeter 6.2 can't distinguish between "shorter wavelength" and "longer wavelength" UVB. It just gives you a Total UVB reading.
So... for some tubes and quite a few mercury vapour lamps, you don't want to match "full sunlight" values, with a Solarmeter 6.2 reading, because although (for example) 300 µW/cm² of sunlight is typical of sunlight at about 9.30 - 10.00am in the tropics, and safe enough.... 300 µW/cm² of UVB from some lamps would contain far too much shorter-wavelength UVB, and could even be hazardous for delicate eyes and skin.

The Solarmeter 6.5 is designed to respond more strongly to the shorter wavelength UVB (by a filter selectively reducing the longer wavelength UVB that reaches the sensor) its readings from lamps and from the sun are much better correlated.
So it is possible to "match" lamp and sunlight readings and be fairly certain that with a good quality lamp, the UV Index you are reading at the tortoise's basking level isn't far off the same "strength" as sunlight giving you the same reading.

Lots of people have asked me if there's a simple formula for converting a UVB reading (µW/cm²) from a 6.2 meter into a UV Index reading.
I wish there was! But because each brand of lamp has a slightly different spectrum, and "new improved" products will doubtless have new spectra too, it's an everlasting game. The only way to do it is to take sets of readings from a lamp, at the same distance, from both meters and plot a graph, from which you can get what's known as a regression formula... (a conversion formula).
Here are some samples, i.e., conversion formulas I've worked out for some lamps I've tested in the last three or four years, using my pair of Solarmeters. You're welcome to use these formulae but please bear in mind that there's no way I can be certain that your lamps are exactly the same as mine; and I only did the calculation on a tiny sample of lamps. So it's not really more than an estimate... (If anyone has 2 meters and some lamps, and wants to set to work plotting some more... please do!  )

So: To get the approximate UV Index from a Solarmeter 6.2 reading, divide the Solarmeter 6.2 reading by the following numbers:

For a ZooMed Reptisun 5.0 or an Arcadia D3 6%UVB tube: 31.4 (average calculated from 4 lamps)
For a ZooMed Reptisun 10.0 or an Arcadia D3+ 12%UVB tube: 32.7 (average calculated from 14 lamps)
For a 100watt ZooMed Powersun : 12.2 (average calculated from 5 lamps)
For a 125watt ExoTerra Solar Glo: 19.4 (average calculated from 3 lamps)
For a 160watt ExoTerra Solar Glo: 16.7 (average calculated from 2 lamps)
For an ExoTerra SunRay Metal Halide lamp: 36.6 (average calculated from 2 lamps, one 50W and one 70W)

To find out what the approximate Solarmeter 6.2 reading would be, at a specific UV Index, multiply the numbers by the UV Index you need.
e.g. if you want a UV Index of 2 under a ZooMed Reptisun 5.0 tube, multiply 31.4 by 2.
So UVI 2 would read about 63 µW/cm² under a ZooMed Reptisun 5.0 tube....
.....ok?

For the sun, it's really complicated because it changes depending on the height of the sun in the sky. My formula requires a calculator!
But here are some calculations I made based on a large number of paired solar readings plotted on a graph...
UVI 1 = 57µW/cm²
UVI 2 = 108µW/cm²
UVI 3 = 155µW/cm²
UVI 7 = 301µW/cm²
UVI 12 = 437µW/cm²
UVI 15 = 521µW/cm²

For example.... suppose I wanted to create a basking zone with a maximum UVI of 3. This is like early morning sunshine about 8.30am in the tropics.
If I was measuring sunlight the Solarmeter 6.2 might read about 150 µW/cm².
To match that, I would need approximately:
98 µW/cm² with a ZooMed Reptisun 10.0 (3 x 32.7)
37 µW/cm² with a 100watt ZooMed Powersun (3 x 12.2)

Does this make sense to anyone or have you all lost the will to live 




Yes, this is what the Solarmeter 6.2 excels in. Take measurements always at the same distance from the lamp, about once a month and you will be able to see how the UVB gradually declines with age.
In the first month, most lamps lose quite a lot, but after that the output from a good quality lamp of most types remains quite good for about a full year, only declining quite slowly... It's usual to replace a lamp when it's lost 50% of the UVB it had at first. With some types, e.g., ones that don't put out a lot of heat, you can keep the basking zone UVB the same over the year by lowering the lamp a little, as necessary, as its output falls.
By taking monthly readings you may discover that some good quality bulbs will keep going for well over a year, without needing changing.
Or when they are getting a bit low for a sun-basking species, you can use them over a shade-dweller - people can sometimes get 2 or even 3 years of life out of a good lamp in this way.

Best wishes,
Frances

Thank you for the tips, I am sure that would help raising the temps. After playing with the setup further I see a major limitation: The distance of 10 inches allows for only one 6% tube. For an enclosure of my size the UVB basking area is a bit narrow (since the tube is oriented perpendicular to the long axis of the enclosure, see pic). The UVB basking area produced is even smaller than the one my mvb makes.

I guess that this would be great if the tubes would cover a greater surface in my enclosure but the glass covers make this diffecult.
 

mikeh

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What are you figuring for UVB width coverage of the tube. Even if the tort sits few inches to either side of the tube its still getting UVB, even though the UV index will be slightly lower.

You can also use Zoomed T5HO 5% which has slightly lower UVB output.
If two tubes are placed in the outer positions of the fixture they should be spaced about 10" apart. This will create higher UV index where their range overlaps directly in the middle, and only slightly higher index on the sides, but the combined UVB is coming from different angles. Now if the tubes are placed directly next to each other, yes the UVB will be much higher. Finally, raising the fixture one more inch will reduce UVB further, but you would have to tweak getting the temps up.

Just a note. I have an 8 month old leopard under Arcadia 12% at 12" distance. He loves spending time (4-7 hours a day) directly under the bulb despite plenty of space elsewhere and is fine.


You could also experiment with taking the reflector out which will reduce the overall UVB output, but I am not sure by how much and what effect will that have on the temps. and ballast which is placed behind the reflector.
 
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