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Old 07-12-2012, 01:40 PM
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Default Need an LED Expert

I have access to a very good LED engineer. I talked to him about what I wanted to do and he started asking me questions I could not answer. He is very interested in enginnering and designing a ligth that meets the demands of what is needed for my future frogs and plants. I'm planning on standardizing on exxo terra vivs 24x18x24. Any help on what is needed to make the perfect led light if you could have whatever you wanted.
Here are some of the things he was asking about:
CCT
CRI
Lumen
Foot-Candles
He did not ask about colors, but he designs led for the office environment not for vivs.So anything I can get would be great.
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Old 07-12-2012, 01:55 PM
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Default Re: Need an LED Expert

not sure how much of an expert he is ? being CCT and CRI are both measurements of color in lighting (CCT is more appropriate for LEDs). once again Foot Candle and Lumens are both measurements of brightness. yes there are slight differences between the two but when asking you your requirements only one of each above is required, BUT FC with the right equipment can be verified in your tank if need be.
for a viv i would say about 1600FC at the top of the viv will do you well. next you need to meet the colors, see chart i made below

the colorful part is a 50/50 mix of warm white LEDs and white LEDs. this was the closest mix of LEDs i could get that made light plants wanted and was pleasing to look at.



if he can figure out how to add UVB to this then he'll succeed where i have failed.
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Old 07-12-2012, 02:48 PM
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Default Re: Need an LED Expert

Quote:
Originally Posted by motydesign View Post
not sure how much of an expert he is ? being CCT and CRI are both measurements of color in lighting (CCT is more appropriate for LEDs). once again Foot Candle and Lumens are both measurements of brightness. yes there are slight differences between the two but when asking you your requirements only one of each above is required, BUT FC with the right equipment can be verified in your tank if need be.
for a viv i would say about 1600FC at the top of the viv will do you well. next you need to meet the colors, see chart i made below

the colorful part is a 50/50 mix of warm white LEDs and white LEDs. this was the closest mix of LEDs i could get that made light plants wanted and was pleasing to look at.



if he can figure out how to add UVB to this then he'll succeed where i have failed.
Maybe you should do the design for me**S** I'm hoping to have something design that well have a dawn to dusk feature. 4 hours on for dawn with a 2 hour overlap of the daytime lights (6 hours) then 4 hours dusk with a 2 hour over lap. Given me 10 hours of light total. With a power up on the dawn side and a power down on the dusk side. What do you think of adding a uvb for either the dawn or dusk side of the unit? Just thinking out load on my keyboard here. I was also thinking about a moonlight mode that would only be used maybe every three days or something like that? Small fans to cool the unit. So what do you think, can it be done??
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Old 07-12-2012, 02:51 PM
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Why not just have a single T5 uvb bulb come on for a couple hours at midday? Simulating the sun at its strongest.... just a thought. I'm no expert by any stretch of the imagination
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Old 07-12-2012, 03:09 PM
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Default Re: Need an LED Expert

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Why not just have a single T5 uvb bulb come on for a couple hours at midday? Simulating the sun at its strongest.... just a thought. I'm no expert by any stretch of the imagination
I may end up doing this. I just want to see waht some real experts can come up with. I'm sure zoos are doing things like this and I was trying to see if something for the average person can be pulled off. I am going to do this to see if it can be a cost savings or at least a break even based on a 10 year period. If I can show a cost savings for that period and have something really cool, I'm sure other people here would be interested in doing the same thing themselves.
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Old 07-12-2012, 03:16 PM
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Default Re: Need an LED Expert

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Originally Posted by jacobi View Post
Why not just have a single T5 uvb bulb come on for a couple hours at midday? Simulating the sun at its strongest.... just a thought. I'm no expert by any stretch of the imagination
i ended up doing something similar since i couldnt figure out the LED option. Im using a 9w lamp thats on 2.5 hours mid day. had to get a whole new ballast set up and such. still working on the top of tank fixture but its coming together little by little.

kinda shows a rough idea of what i was doing when i first started.
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Old 07-13-2012, 04:01 AM
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Default Re: Need an LED Expert

New on here, but have been researchin LEDs for some time. The reefers have plans for building controllers for different circuits to simulate the exact light cycle you are after.

In addition they do have LEDs that emit UV light. The current/amp requirements will mean they avevto have their own circuit.
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Old 07-13-2012, 04:08 AM
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Default Re: Need an LED Expert

my viv is doing well at 100 lumens at the floor. if he can replicate this with a nice led array you will do well. i also would recommend mixing cool white with warm white leds at a 2 to 1 ratio. adding uvb would be very cool but they seem very pricey. at 24 inches deep you will probably want 60 degree optics. let us know what he come up with.
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Old 07-13-2012, 04:28 AM
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Default Re: Need an LED Expert

WOW Lookie what I just found UV leds are getting better and cheap too
Cutter Electronics
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Old 07-13-2012, 12:32 PM
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Default Re: Need an LED Expert

Contact Todd at Light Your Reptiles. He knows a lot about the LEDs. Instead of running my UV bulb at midday, I run it first. I do this because it is just one bulb. It creates a "morning" light that is not as bright as all my LEDs. Plus, it is on when the frogs seem most active. I also run the UVB for an hour before bed to have a "sunset" effect. Again, this is a time they seem pretty active. It doesn't do any good to run a UV bulb when they are hiding
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Old 07-13-2012, 01:13 PM
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Default Re: Need an LED Expert

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Originally Posted by bobrez View Post
WOW Lookie what I just found UV leds are getting better and cheap too
Cutter Electronics
While that produces UV lighting, it produces the wrong wavelength. That range is well short of the ideal range to allow an animal to manufacture D3.. You need a wavelength below 320 nm (with the sweet spot being around 285-298 nm) which is very different than what those leds are producing.

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Old 07-13-2012, 02:31 PM
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Default Re: Need an LED Expert

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Originally Posted by Pillguy View Post
New on here, but have been researchin LEDs for some time. The reefers have plans for building controllers for different circuits to simulate the exact light cycle you are after.

In addition they do have LEDs that emit UV light. The current/amp requirements will mean they avevto have their own circuit.
not sure if they are using the right leds? you have a link?

Quote:
Originally Posted by bobrez View Post
WOW Lookie what I just found UV leds are getting better and cheap too
Cutter Electronics
the 300-440 if available might be helpful, but really it needs to drop a few more wave lengths for maximum functionality as 285-400 is whats needed, on top of that id like to see a spectrometer reading of the 285-400 if it ever comes out so i knew what the peaks and valleys were and to see what the intensities are?

Quote:
Originally Posted by jeeperrs View Post
Contact Todd at Light Your Reptiles. He knows a lot about the LEDs. Instead of running my UV bulb at midday, I run it first. I do this because it is just one bulb. It creates a "morning" light that is not as bright as all my LEDs. Plus, it is on when the frogs seem most active. I also run the UVB for an hour before bed to have a "sunset" effect. Again, this is a time they seem pretty active. It doesn't do any good to run a UV bulb when they are hiding
there is some info i have read that suggests changing that schedule to mid day will change their behavior and they will come out to self regulate the UV intake.

Last edited by motydesign; 07-13-2012 at 02:33 PM.
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Old 07-13-2012, 02:32 PM
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damn it Ed, beat me too it!
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Old 07-13-2012, 06:34 PM
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there is some info i have read that suggests changing that schedule to mid day will change their behavior and they will come out to self regulate the UV intake.
Well actually the frogs have a daily bimodal activity under natural conditions. They are most active in the morning and in the late afternoon. Now whether this is a result of conditionally attempting to avoid excess UV exposure or due to other factors (say temperature), can still be debated...

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Old 07-13-2012, 06:38 PM
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ahhh i see, i have been reading too much on the UVB side that could be bias rather than using Occam's razor.

while in panama for what was too short of a time, it seemed that activity under the canopy was pretty high from dawn to dusk(only pumilio sp) (and surprisingly to me calling even hours after dark)

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Old 07-13-2012, 06:51 PM
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Default Re: Need an LED Expert

My pumilio will call at night if there is a bright moon outside. I've had leucomelas call at 2-3 AM.
See JSTOR: An Error Occurred Setting Your User Cookie (not free access)
abstrat quoted here
Quote:
Abstract:
Activity of Dendrobates auratus and D. pumilio in northeastern Costa Rica was monitored at 45 min intervals throughout daylight hours on nine days in late-June and early-July 1997. Activity of D. pumilio peaked early in the morning, declined steadily to mid-day, then remained at a relatively low level through the afternoon. Activity of D. auratus peaked in early afternoon, and was more consistent throughout the day than was activity of D. pumilio. There was a clear peak in use of elevated perches by D. pumilio, which occurred shortly after sunrise, although no such pattern was evident for D. auratus. A significant positive relationship between rainfall and activity was evident for D. pumilio, but not for D. auratus. These data demonstrate differences in activity patterns between these congeners, in spite of many ecological similarities
also http://www.natuurwetenschappen.be/en...%20105-109.pdf...

Keep in mind that those descriptions are for most of a population and not all of the animals may engage in the same temporal partioning...

Ed


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Old 07-13-2012, 11:05 PM
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While that produces UV lighting, it produces the wrong wavelength. That range is well short of the ideal range to allow an animal to manufacture D3.. You need a wavelength below 320 nm (with the sweet spot being around 285-298 nm) which is very different than what those leds are producing.

Ed
thank you ed.
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Old 07-13-2012, 11:24 PM
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there is some info i have read that suggests changing that schedule to mid day will change their behavior and they will come out to self regulate the UV intake.
yes ... my variabilis all do.

remember, dart frogs don't need allot of UV.

I shoot for about 25-50 Uw/cm2 in just PARTS of an enclosure.. and below 10 in the rest.
Full Mid day sun is 260 - 300 Uw/cm2 in the tropics - but you do NOT want to have that in an enclosure at all.

It is very interesting to take a solarmeter out and measure the UV in dappled sunlight like what comes through a leaf canopy and creates patches of high light/UV and low UV shady Zones.
Ferguson Zones.

Please feel free to e/m with any questions, but PM-ing is not so good because I forget to check sometimes. LOL.

Cheers!

Todd Goode
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PS.
Even though you could get a huge debate going, I say the BEST method is to have screen holes or screen strips in the glass tops with the GOOD Uv bulbs (like Arcadia or Repti Sun CFLS) over the screen holes.
Some folks use Solacryl and thats cool...
But with the glass and holes, you are in effect creating MINI Ferguson Zones of high and low UV in the tank, JUST LIKE NATURE.
Word to ya' motha.
And there is far less risk in over-doing it... since most folks are uv-ing without a Solarmeter 6.2 (or 6.5). Like driving with-out a seat belt!
ps... note uv readings in grow out tank pics (2 pics) below once you move the solarmeter 6.2 around under the screen holes vs just the glass.
The lid on this 18gal. tank is the Aqu. lid in teh pic that has 5 screen holes drilled in the glass and is being lit with an Arcadia 12% t8 Bulb.
The 12% is too high to use over solacryly, but because most of the UV is getting knocked out by the glass, it the the right choice for THIS particular set-up.
Attached Images
File Type: jpg 20 UV levels in grow out tank 2.jpg (88.5 KB, 19 views)
File Type: jpg aaauvlid.jpg (85.8 KB, 17 views)
File Type: jpg screen uv holes.jpg (83.0 KB, 18 views)
File Type: jpg uv reading with full light ON.jpg (87.4 KB, 11 views)
File Type: jpg new solarmeter.jpg (45.9 KB, 8 views)
File Type: jpg 19 uv levels in growout tank 1.jpg (90.8 KB, 12 views)
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Old 07-14-2012, 12:36 AM
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todd i agree with some of this info how ever i still feel that the solarmeter6.2 and 6.5 isnt the right tool for the job. yes it gives you a uw/cm2 number, but is that measuring a the uw/cm2 of 340nm or is that heavy 280nm, or is it some where in between? well with that tool youll never know. with out a true spectrometer providing information like this you are still "driving a car with out a seat belt"
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Old 07-14-2012, 01:58 AM
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todd i agree with some of this info how ever i still feel that the solarmeter6.2 and 6.5 isnt the right tool for the job. yes it gives you a uw/cm2 number, but is that measuring a the uw/cm2 of 340nm or is that heavy 280nm, or is it some where in between? well with that tool youll never know. with out a true spectrometer providing information like this you are still "driving a car with out a seat belt"
Hi Motlydesign,

The Solarmeter 6.2 is still the best that is readily available to most hobbyists and the band sensitivity can be viewed at the Solarmeter site.
(along with the 6.5's sensitivity as well.)

You have got it ALL wrong to say it is still like driving without a seat-belt.
(Sorry, but it's true.)

It is driving with a seat-belt... now, maybe it is NOT a 5 point harness...
I would grant you that....
But it is the standard* that is used for what we do.
And also the readings are probably one of the more universal references in the herp community.

* Solarmeter 6.5 not with-standing.

Actually correlating the reading ratio between a 6.2 and 6.5 seems to be the better thing to do now, and the buzz for Europe surrounding the 15-1 ratio between the 6.2 & 6.5 reading.... but not everyone has access to, or can afford both.

I would point you to Frances Baines site for more on that.

UV Guide UK - Ultraviolet Light for Reptiles - UVB reptile lighting on test

Finis.

Cheers!

Todd
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Old 07-16-2012, 03:01 PM
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Todd,
i understand that you believe in these meters, but what im saying is irrefutable.
you meter is NOT capable of stating what wave length is being produced by the lights.
i understand this is your business and you sell the product and have something to gain from your stand point. so :

is this better than nothing? yes
Are you provided the full story with a 6.2 and a 6.5 using your method above? no, it would cost a person $2,500 min to get the full story (thats a jagged pill no one wants to swallow)

anyway i know im dragging this out past the point that i should, thanks for bearing with me on it. Id love to see some one in the US buy the right equipment and bench mark the common lamps that are used. meaning:
6.2 reading is taken of a lamp, a uw/cm2 is given
same lamp is then mapped with a spectrometer.
next let the lamp burn for a 1 month repeat the steps above. do this for 12 months.
at this point the $200 would tell me very close to what i am getting at each measurement.

If this was done to lamps a vendor sold i would def buy the 6.2 and the same lamps over and over again!
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Old 07-17-2012, 03:57 AM
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anyway i know im dragging this out past the point that i should, thanks for bearing with me on it.
boy you sure are....
LOL.

Sorry dude, but I gotta set you straight so you don't miss-inform / miss lead others on this subject.

I have been UV-ing herps since I first started using the old GE Time-a-tan bulbs in the late 70's over leopard tortoises (that was when you had to use your own body parts to test exposure times because there were no meters.)

Stick your arm under the bulbs, measure the distance...and watch the clock.

And then compare the tan (or burn!) you got with how much you would get in mid day sun in summer with the same exposure time.
Crude.. ? .. yes.
But that was all us old-timers had to go by ....to test on ourselves BEFORE risking anything on our animals.
And since then I have been in on correctly applying UV for the past 30+ years.

Now, Motlydesign...
can you share with us what exactly IS YOUR experience level in this area?

Since you feel the need to be " dragging this out past the point that i should".

How many different UV products (bulbs, meters, etc) have you tested and used over the past say 30+ years?

And you seem to insinuate that I am promoting them because I sell them.
You are sure right there!
I do promote them!

And since you want to have the last word and be the internet expert on this thread....

maybe you would like to tell the folks how much I make off them selling them at 168.97?
BTW, The cost direct from Solarmeter is 219.00. (!!)
I sell them and take the lowest mark-up possible because I believe they are the best tool that is readily available.... and more folks should own them and be educated in their use.
I certainly am not lining my pockets selling them at quite possibly the lowest retail price in North America.
I try and do my part to make them as affordable as possible so that everyone who needs one can hopefully afford one.
Because their animals will benefit from it.

So when I tell folks a Solarmeter is a good investment for a serious herp keeper, (no matter where they choose to buy one), that IS advice they can bank on.

Cheers!
Todd
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Old 07-17-2012, 02:06 PM
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First of all this is why i go stents with out posting on this site.

to answer your question, MY level of experience IS an Electrical And Mechanical Engineering degree, 10 years of designing electrical products for the company I own and 8 years working with Chams. does this mean anything? NO!!! it doesnt matter one bit with the world of GOOGLE information is readily available for ANYONE that has access to a computer. and calling yourself a UV expert because of 30 years of sticking your arm under a light is like saying im a vet cause ive stuck my arm up a cows ass for 30 years... completely irrelevant!

in regards to your mark up, this once again is irrelevant.

so now that we have compared whos is bigger lets JUSTtalk facts and leave emotion out of it

is suggesting owning one sound advice, YES (as i stated JUST the post above yours, this is better than NOTHING)



Now lets talk why you didnt address my proposed solution a vendor could take. I stated that the tool would become WELL worth its cost if some one would bench mark their systems.

The reason i state this is because the wavelengths produced degrade at different rates. this being said, the important 280-290 area on a bulb offered by a vendor is shown on the back with the factory spectrometer reading along with all the others. HOWEVER after 10 hours of burn time what if the 280-290 dropped to 1/4 the initial value (this is an exaggeration to make a point) where the rest of the light stayed pretty close to the same intensity readings across the 290-320 wave lengths. using a 6.2 or a 6.5 would show very little has changed but if this bulb had been bench marked we would know that it was time to replace the bulb instead of trusting the reading from their 6.2.

All ive stated from the start is that the 6.2 gives a false sense of comfort to the user if they dont have the full story of what their bulb is producing when they look at a simple number reading.

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Old 07-17-2012, 06:42 PM
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The reason i state this is because the wavelengths produced degrade at different rates. this being said, the important 280-290 area on a
Point of clarification... the important range is @280-315 with a maximal conversion rate around 298 but we should keep in mind that the effective range is much wider (as low as 280 and as high as 315).

I think this paper may help with the discussion. It is free acccess http://mail.solarmeter.com/pdfs/paper3.pdf

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Old 07-17-2012, 06:50 PM
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Thank you Ed, I see your point with posting that clarification. I was trying to just point out that lamps don't degrade at even rates across the spectrum.
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Old 07-17-2012, 06:52 PM
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Thank you Ed, I see your point with posting that clarification. I was trying to just point out that lamps don't degrade at even rates across the spectrum.
I understand your point as well as Todd's, hence the paper since it seems to be exactly what you both are discussing. Thanks for not taking it personally.

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Old 07-17-2012, 07:08 PM
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ill be honest i was trying not to at first, but as always internet conflicts seem to bring out the worst in people (myself included). looks like i need to put my money where my mouth was and buy one from lightyourreptiles.com on my next paycheck.
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Old 07-17-2012, 07:15 PM
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Very interesting read here on this thread. Way more info on lighting then I ever would have thought. I am really pleased with finding this site. You can get into so much more detail than just being a pet owner and this was exactly what I wanted.
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Old 07-17-2012, 08:08 PM
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whoever thinks lighting is a "dull" subject will need to visit this thread!
thinking about lights sure keeps me jazzed up. ha ha.
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Last edited by Venutus1; 07-17-2012 at 08:25 PM.
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Old 07-17-2012, 08:09 PM
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Default Re: Need an LED Expert

Those test are old but helpful
Can we get any benchmarks for bulbs out nowadays.

Quote:
Originally Posted by Ed View Post
Point of clarification... the important range is @280-315 with a maximal conversion rate around 298 but we should keep in mind that the effective range is much wider (as low as 280 and as high as 315).

I think this paper may help with the discussion. It is free acccess http://mail.solarmeter.com/pdfs/paper3.pdf

Ed
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Old 07-17-2012, 08:20 PM
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Default Re: Need an LED Expert

Quote:
Originally Posted by bobrez View Post
Those test are old but helpful
Can we get any benchmarks for bulbs out nowadays.
Actually, the benchmarks for newer bulbs are unimportant if you use a 6.4 since
Quote:
The Solarmeter 6.4 is an inexpensive broadband UVB
meter that adequately describes the quantity of D3-synthesizing
UVB.
.... The ability of the exposure to UVB to enable D3 synthesis is more important than knowing the exact spectral out put of the bulb.......

Ed
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Old 07-17-2012, 08:40 PM
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Quote:
Originally Posted by Ed View Post
Actually, the benchmarks for newer bulbs are unimportant if you use a 6.4 since .... The ability of the exposure to UVB to enable D3 synthesis is more important than knowing the exact spectral out put of the bulb....... [/SIZE]

Ed
[/SIZE][/FONT][/SIZE][/FONT]
Not looking for spectral out put quess i'd like some recomedations on bulbs with UVB to enable D3 synthesis
If anyone had done testing with available bulbs im sure that Todd has
I just dont know which
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Old 07-17-2012, 11:38 PM
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Hi, everyone.

Todd has just asked me if I'd visit your forum to see if I can answer some of the questions you've been asking about the meters, vs. the spectrometer. This is a lively discussion I see
So I hope what I can offer, is useful....

Both Todd and Motydesign have made some equally good points about the pros and cons of broadband meters.
Ed has added some excellent material too. The lamps in the paper he mentions, though, are almost all either no longer sold, or different from current models.
One thing I'd also point out before I ramble on about meters, is that although "280 - 315nm" is often quoted as the "optimum" range for vitD synthesis, natural sunlight has NO UV at ALL below 290nm and wavelengths below about 295nm are only found under an overhead sun close to the equator... so basically, at the times reptiles and amphibians expose themselves to sunlight, (mainly early-mid morning and late afternoon) the shortest wavelengths - which are the most photo-reactive - are probably no shorter than 295nm. This is why lamps emitting wavelengths below 295nm are inherently more risky... and ones emitting anything below 290nm - "non-terrestrial UVB" - pose a much greater risk of skin and eye damage and in my opinion are unsuitable for use with living things.

But... about these meters.

To assess the safety and suitability of a UVB lamp for use in a vivarium, two pieces of information are needed:
1) The Quality of UV (its spectrum - the wavelengths emitted) and
2) The Quantity of UV (its intensity at different distances, and the shape of the beam).

A spectrometer is essential to assess (1) the Quality. No broadband UVB meter, however expensive and "accurate", can indicate whether a lamp is emitting hazardous short-wavelength UVB below 290 - 295nm; or whether the lamp is only emitting long-wavelength UVB, e.g., from the 313nm mercury emission, which will enable synthesis of vitamin D, but requires a far greater intensity to stimulate adequate synthesis than wavelengths around 300nm.
However, few hobbyists would consider spending several thousand dollars on a spectrometer - far better to seek out independent lamp test reports which show the spectra of different brands, and choose those with good, safe spectra.

Broadband meters, however, are vital to measure (2) the Quantity: the intensity of the output at different distances, and the shape of the beam. Even a lamp with the most perfect spectrum can be either useless or dangerous, for example, if the beam is too narrow, or the lamp is too close, or too far away. A spectrometer is not a practical instrument to do "spot checks" in a vivarium... and cannot be used to map out the shape of a beam or a UV gradient.

The way that a broadband meter works, however, leads to problems because by its very nature, it responds to a broad band of wavelengths. Most UVB meters use silicon carbide as a sensor, with an interference filter blocking out unwanted wavelengths of light so the electricity generated is as far as possible due to "UVB"; and the readout is calibrated from values measured by spectrometer. But of course, filters and sensors vary slightly, even between batches. Every single brand of UVB meter, however expensive, has a slightly different response curve, responding to slightly different wavelengths in different ways....and every single brand is calibrated to a specific light source, too... and these are not all the same, either. Meaning that if you aim samples of 4 different brands of UVB meter, even the best laboratory-grade meters, at the same reptile lamp you will get 4 different results.
This is not very helpful.

Likewise, some UVB meters (the very cheap ones sold for a few dollars for "safe sunbathing") actually respond to UVA not UVB - because there is an order of magnitude more UVA than UVB in sunlight, and there is some correlation between the levels of the two. Obviously, the readout has been designed to approximate the estimated UVB but it's pointless using these for UVB lamps, which have a very different spectrum.

The first meter we could buy that was reasonably accurate, yet still affordable, was the Solarmeter 6.2 UVB meter,
Welcome to Solartech.
This meter estimates the total UVB output (it responds to wavelengths from UVC right up to and including a little short-wavelength UVA at about 330nm) and gives a reading in microwatts per square cm (W/cm).
It's a good little meter, sensitive and reliable. I use my 6.2 all the time, to monitor decay and to work out the shape of a lamp's beam.
It's got very high precision - 1W/cm - so it is extremely useful for fine monitoring of decay in any one lamp, since the shorter wavelengths of UVB decay at a reasonably similar rate to the longer wavelengths - but you can't use it to decide whether one lamp is better or safer than another, or compare a lamp's vitamin D3-making potential with that of sunlight.
This is because it reads from too wide a band of the UV spectrum. Since it responds to everything from UVC to short-wavelength UVA, in theory, if one lamp has a lot of its UVB in the shorter wavelengths, whereas another has a lot of its UVB in the longer wavelengths, they could both give identical readings with a 6.2, but the first lamp might be much better at producing vit D3 than the second one....

To find out a lamp's vitamin D3-making potential, you either need to use the spectrometer and integrate the resulting spectrum with the action spectrum of vitamin D3 synthesis, or you need a meter that has a sensitivity response as close as possible to the action spectrum for vitamin D3 synthesis. This peaks at the UVB threshold of tropical sunlight - about 298nm - and falls to a low level at wavelengths above 315 - 320nm.

Fortunately for us, Solarmeter make just such a meter, it is the 6.5 UV Index meter.
Welcome to Solartech
The UV Index (UVI) is an internationally-recognised, unitless measurement of the intensity of the photoreactive part of the spectrum of sunlight (or any light containing ultraviolet). It is based upon an integration of the spectrum of the sunlight (or lamp) with the action spectrum for human erythema, ie., sunburning.
Of course this is totally irrelevent for reptiles and amphibians! ...but that action spectrum is very close to the action spectrum for vitamin D3 synthesis, which of course we ARE interested in.
It's not a perfect overlap, but it provides a good enough match for the UV Index to act as a proxy for the vitD3-producing ability.
And interestingly, the response curve of the Solarmeter 6.5 meter appears to follow the D3 action spectrum even more closely than it does the erythema action spectrum. A physicist friend of mine has calculated that the 6.5 meter's sensor response is a 96% match to the CIE pre-vitamin D3 spectrum from 290 - 400nm. This is pretty impressive for a relatively inexpensive instrument.

The UV Index is a very useful scale to assess a lamp with, too, because the numbers are familiar to many people from "sun safety" reports, and give a useful sense of what intensity is likely to be safe and "sunlike" vs. what is going to be frankly dangerous to eyes and skin of all living things.

The UV Index is appearing on more and more weather broadcasts, and websites with daily forecasts (see links below) - though these often only show "midday maximum" figures, ie. the highest reading you'll get at midday in a fully exposed location, when the sun is at its highest. This is of course NOT when most reptiles and amphibians bask! so these figures are almost useless. The UV Index recorded at the times when basking species lie out in the sun are far more helpful, but even so, these are usually recorded from bare rooftop installations, whereas basking is often done in sunlight between foliage shade... so ideally, we need people out there recording UVI where the animals are. But few studies have been done... yet.
Nevertheless, here are some interesting links. The first UK link has live data, tracking throughout the day, and the Australian individual town forecasts appearing in pop-up windows are predictions for clear skies, but show the rise and fall over a whole day.

USA UV Index | SunWise | US EPA
UK HPA - UV Index Graphs
and examples at:
HPA - Typical UV readings
Australia UV and Sun Protection services (intro) and
Ultraviolet (UV) Index Forecast (forecasts)

I now use the 6.5 UV Index meter, along with the spectrometer, to estimate a lamp's vitamin D3 potential - and safety.

Hand-held meters can never be "accurate" in the same way that a spectrometer can be, but they are for assessing Quantity, not Quality, as I've tried to explain. From a practical point of view, I believe that a Solarmeter 6.5 is more than adequate for roughly matching the output of a lamp with a known, "good" spectrum with that of sunlight, when setting up a UV gradient in a vivarium indoors.
It has proven effective in trials measuring vitamin D3 output in vitro, and new recommendations for suitable UVB gradients in vivaria are being developed based upon field studies recording the UV Index in the microhabitat of numerous species in the wild; see:

Ferguson et al. (2010) Voluntary exposure of some western-hemisphere snake and lizard species to ultraviolet-B radiation in the field: how much ultraviolet-B should a lizard or snake receive in captivity?
Zoo Biology 29(3) 317-334
Voluntary exposure of some western-hemisphere snake and lizard species to ultraviolet-B radiation in the field: how much ultraviolet-B should a lizard or snake receive in captivity? - Ferguson - 2009 - Zoo Biology - Wiley Online Library

I am currently working with a team from UK zoos, to develop a guide to suitable UVI levels for animals inhabiting different UV "zones" as described in that paper; these will be called the Ferguson Zones. They range from Zone 1 - crepuscular and shade dwellers - to Zone 4 - "sun-worshipping" midday baskers. This guide is due to be launched at the end of this year.

All the best
Frances
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Old 07-18-2012, 02:40 AM
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Thank you Frances for taking time out of your busy schedule to visit us here on Dendroboard and educate both Brian (motydesign ) and myself (and the rest of the readers of this thread) on UV and UV meters.


Plain words and thank yous are not enough to express the gratitude the herpetological community has for your work.

And for all the contributions you have made and continue to make towards improving the care of captive reptiles and amphibians worldwide.

Most Sincerely,
Todd
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Old 07-19-2012, 01:15 AM
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Just check my thread. Don't need to get into the mamma mamma of the science that much. Just get the spectrum and intensity and your good. My growth is explosive.
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Old 07-19-2012, 09:05 AM
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Hi, Giga.
Quote:
Just get the spectrum and intensity and your good.
Spot-on, Giga.
Your plants look fantastic, very healthy.

But your LEDs cannot supply the spectrum needed for vitamin D biosynthesis in your frogs. I've looked into the spectra of existing "UV" LEDs and there are none suitable as far as I know. You actually need a broad spectrum from 295-320nm and LEDs by their very nature emit on very narrow spectral bands - unless a fluorescence is being utilised, as with "white" LEDs.... I don't think anyone has invented a suitable UVB fluorescence for LEDs, but they certainly have for ordinary fluorescent tubes.

I don't know how much natural sunlight the species you're planning will need - but I'm certain others will be able to advise you there. I suspect you will simply need to add a good quality UVB-emitting fluorescent tube or compact lamp. Brands with spectra in the correct range of wavelengths and low intensity UVB include the ZooMed Reptisun 5.0 and Arcadia D3 6%UVB. Don't go for anything very cheap. Some Chinese-manufactured brands emit shorter wavelengths, and/or poor quality build.
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Old 07-20-2012, 03:00 PM
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I never do cheap led because I tried that at first, and they suck. UVB and uv in general is blocked by glass so to tell you the truth I'm not worried about it. And leds spectrums are not as narrow as you think.



If you scroll down to page 15 you see that my cool white has more spectrum then you think.
http://www.bridgelux.com/assets/file...5%20120311.pdf
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Old 07-20-2012, 03:44 PM
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Giga, they are talking about UVB LEDs , they are the ones with pretty narrow spectrums. They are getting better every month it seems like, but still pretty narrow.
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Old 07-20-2012, 04:48 PM
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Yeah I understand, but with full led spectrum like I got you'll be fine and no need to worry so much.
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Old 07-20-2012, 08:00 PM
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Hi, Giga.

Thanks for the link to your Bridgelux Data Sheet.

Compared to natural sunlight, all "white" LEDs - as in Fig. 4 in the Bridgelux Data Sheet - are deficient in all wavelengths above 600 - 650 nm, in "cyan" (between 460 -510nm) and in deep blue/ purple (below 440nm).
Your red and deep blue LEDs as mentioned in your previous post, should compensate for the 600-650nm and 380-440nm deficiencies.
But true "cyan" LEDs - i.e. ones that actually supply the correct wavelengths, rather than simulate the colour for human eyes - are very difficult to obtain. I have not seen a good one yet.... have you? That is probably the only gap in your "visible" spectrum.

However, UVA and UVB are necessary for normal amphibian vision and for vitamin D3 synthesis, respectively. They are blocked by normal glass and most plastics, just as you say.... this is why special UV lamps are necessary, and why these must be placed in the terrarium with no glass or plastic shielding. At present these wavelengths cannot be obtained from LEDs in the necessary wavelengths and intensities for vivaria - that's my point. I'm not saying your visible light is a problem, quite the opposite, it looks very good.

Best wishes

Frances
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