Anyone Thinking of Dumping LEDS and going back to Halides

This from wikipedia:
The lamps consist of a small fused quartz or ceramic arc tube which contains the gases and the arc, enclosed inside a larger glass bulb which has a coating to filter out the ultraviolet light produced.[1][3] They operate at a pressure between 4 to 20 atms, and require special fixtures to operate safely, as well as an electrical ballast. Metal atoms produce most of the light output.[1] They require a warm-up period of several minutes to reach full light output.[2]

The bulb itself filters out the UV, not the glass lens used.
That is why my lens is Lexan, not glass.
It is cheaper and much easier to work with than glass.
 
With this signature you are pointing fingers?
............And then the cops showed up

Remember when you point a finger there are three pointing back at you.

We are not "debating" we are discussing facts sir.
 
SE bulbs rely on the outer glass for UV protection, DE bulbs rely on a separate shield on the fixture to block out the UV.
 
Sirreal63 is correct if a shield is cracked on a se halide bulb it will bleach out the coral below it. It happened to a friend of mine who couldnt figure out why his corals suddenly bleached. Found the MH bulb glass was spilt.
 
When the first LED fixtures for aquarium first came out several years ago, everyone said that they don't heat up the tank, but when I saw one in person, the thing was just as hot as my halides. Several years later (now in 2014) I came back to the hobby and found that LEDs are much more common now, and I thought that the technology had improved. I saw a "Kessil" spotlight in my LFS and ran my hand under it.. the thing is still hot just like metal halide. I thought LEDs don't heat up at all? Is this just a myth?
 
They get hot to the touch, but they are not nearly as hot/heat emitting as metal halides.
At least Radions are not.

EDIT: Speaking of heat… my post count just hit 4020. :wildone: :smokin:
 
We had a local reefer who took the shields off and clean them before they turned on. He forgot to put them back on and then worked on the tank for a little as they fired up. He didn't think much of it and left them off all day. The next day he woke up with severely burned eyes and had to go to the doctor for it all. It only took a little while of him staring at the bulbs and not being careful. UVA light is very dangerous to us and the corals. We should not be trying to introduce it in any form over our tanks. It's reckless and dangerous to advise its use without the proper knowledge.
 
Look at the spectral plots of either a 20K radium or a 14K phoenix bulb, to name a few common bulbs. Both have output from 350-400 pretty much equal to what they produce from 500-700, without a few spikes. These are easily found by Google.

They absolutely put out UVA. They always have. The water will filter it exponentially as it gets deeper down to about 3M. Since most of our tanks are not even 24" deep, plenty gets to the organisms.

Look through these. These are mogul, so they have the glass in place.
http://www.advancedaquarist.com/2004/8/review
 
jda said:
Look at the spectral plots of either a 20K radium or a 14K phoenix bulb, to name a few common bulbs. Both have output from 350-400 pretty much equal to what they produce from 500-700, without a few spikes. These are easily found by Google.

They absolutely put out UVA. They always have. The water will filter it exponentially as it gets deeper down to about 3M. Since most of our tanks are not even 24" deep, plenty gets to the organisms.

Look through these. These are mogul, so they have the glass in place.
http://www.advancedaquarist.com/2004/8/review
Click to expand...
Not sure what your point is. If the UVA needs to be filtered out by a glass shield to protect both you and our corals, why bother trying to reproduce it?
 
The point is that it does not get filtered out like everybody thinks. It is present in amounts that are similar to the spectrum from 500-700. Those spectral charts are showing output after the filters. IT IS THERE. THE CORALS ARE GETTING IT. YOUR HOUSE IS GETTING IT. IT IS CERTAINLY PRESENT IN THE WILD.

This is important because some coral develop pigments to reflect it and even some might use it and spit back out lower energy bandwidth that looks pretty. As such, any type of lighting that does not produce some of it will have a hard time showing the same color in coral as light that does have it. It does need to be reproduced IMO - don't confuse too much with the right amount.
 
...so you are saying that the lamps used in the tests with the AA article had the glass removed from the mogul bulbs? ...or that when I tested a 20K 400W radium in my own home (albeit with a cheaper spectraradiometer) that the glass shied magically jumped off during the test and then jumped back on afterwards? I might not know anything about cyrstaline structures, but I might be able to suppose that they don't just magically disappear when somebody is testing spectrum. I also know that you can get those same PPFD measurements as the article when testing at home with a bulb as it was manufactured with the glass on.

Off topic, but with your vast knowledge of the interference of crystalline structures to wavelengths, why would anybody test the spectrum of a bulb pre-interference and have a pile of unusable results to people who would never use them that way?

What more factual basis do you need than the charts in the AA article, which were bulbs as they would be used over the tank, as well as a simple search for analysis on UVA water penetration of which there are plenty regarding sunscreen when diving and snorkeling, which few people do in the air at low tide like the supposed corals. I cannot remember which thread it was on, but one of the sponsors took measurements of measurable amounts of 350-400 UV light down to 3 meters in the pacific - maybe Pacific Sun?

Why is it that every post that I see asks for factual basis for claims, research and the like, but never provide any? Perhaps I missed most of them and just caught the ones with decrees of failure of understanding.
 
jda said:
...so you are saying that the lamps used in the tests with the AA article had the glass removed from the mogul bulbs? ...
Click to expand...
Hmm, good point. I too like evidence so I went back to some of the AA articles by Sanjay Joshi. It seems to me that the bulbs that produce more than a negligible amount of UV are the old 65K and 10k bulbs that nobody uses because, well, they produce poor colour in corals. If you look at T5 tubes, there really isn't anything below 400 nm.

I guess I still don't get your point. OK, a Radium bulb has a tiny amount of UV, does it really have any significant effect? Given the colours generated by T5 lighting I would be inclined to think not.

YMMV I guess...
 
T5 charts are hard... most of the ones from ATI show zero in lots of the spectrum when there is some there and the charts emphasize the peaks. Here are a collection of graphs that will show more from 500-700 as well as under 400 in the UV range. Most of those have output below 400 and some even have some small peaks. I don't know many who uses glass under these to filter out the UV. Spectrum from 350-400 is present in T5 too just like it was in VHO and HO bulbs. I wish that we knew if it was negligible, or not, but that is going to be hard when people won't even acknowledge that it is there.
http://www.practicalcoralfarming.com/t5spectrums.html

I guess that my point is that if the UVA is present in bulbs that many think are able to produce more/better color, then the longer that people poo-poo the UV away, the longer that it might take to get them added to a next-generation-light if they are indeed important. Nobody knows if the amount is negligible, or helpful, and I would really like it if somebody did.
 
I don't see the charts as that hard to interpret. They are intensity charts. The huge peaks are where the majority of the light energy is radiated. That the amount of UV showing in those charts indicates that UV makes up a very, very small amount of total light energy. There may well be a way to interpret the data to generate a relatively accurate percentage value, I don't know. I doubt that it would even approach 5%.

As to reflectance, if a coral reflects light you can't see, you won't see it.

The only way you would have a visible effect from UV light is if it is re-emitted in a visible spectrum. I have not seen anything that shows there are any fluorescing proteins below 400 nm. I am curious to know if you have come across anything in that area.
 
Those are standard T5 spectral plots put out from manufactures and an incorrect KZ Fiji Purple spectral plot.

No one has said there is no UV in these lights. What we've said is that there are things put in place to protect us and our animals from that UV. T5s actually produce very little UV light and the majority of that is filtered by the glass on the tubes.

Again, some may be reaching the corals but I doubt it does anything for the corals and their coloration. Lighting is a topic that I've been extremely interested in for about 8 years now. That is not very long to some others and I'm not here to argue with anyone. However, I've spent thousands upon thousands of hours reading almost every lighting article I can find. I like to think I know more than the average guy but am always open to new material and learning.

I've never seen anything prove that UV light was beneficial in any way for coral health. Remember, color doesn't always mean healthy.
 
I think one of the big confusions with people is what really is UV lighting. Dependent on your source of information UV lighting consists of the light with wave lenghts shorter than either 380nm or 400 nm.

Atinic light 440 nm to 400 nm is not UV light as some individuals think and is listed in some product information especially by 2nd and 3rd party LED venders.

UVA light is referred to as light between 315nm and 400nm. Until reciently this light was considered completely harmless to plants and animals. And even today is argued by scientists. When you purchase a black light bulb what your getting is a bulb designed to emit a maximium of its spectrum in the UVA range.

UVB light is refered to as the light between 280nm and 315 nm. This is the light that causes tanning and sunburn as well as attributed to most of the skin cancers.

UVC light is reffered to as the light between 100nm and 280 nm. This is the light that will rapidly break down many living cell structures. When you purchase a UV sterilizer bulb you are getting a florescent bulb designed to transmit most of its light in the UVC range.

As far as glass filtering out UV light There are various factors that need to be considered. Yes glass does reduce UV light but it reduces the shorter wave lengths of UV light better than longer wave lengths. There are also various types of glass which also effect this filtering ability as well as its thickness. If glass were a perfect UV filter then they would not be able to make Black lights and UV sterilizers using glass.

Other products like clear acrylics as well as other polycarbonate also have different filtering abilities for light. These even differ between manufacturer.

Where the disagreement is though on "near UV" lighting is how much is needed and how much is excessive. Yes there are a few corals that will fluoresce from 400nm and some more will fluoresce at 410 nm. But the more important wavelenghts with most of the florescence as well as the photosynthesis are in the 440 to 480 nm range.

If we provide enough light in the 440 to 480 nm do we also need light in the 400 to 440 range and if so how much?
 
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