fans directly on light-harmfull???

[sir_dudeguy]

a few months ago i read that if you put a fan blowing directly onto a light bulb that it will somehow lower the PAR or do something that makes the bulb less efficient/powerfull because it wont heat up to the proper opperating temperature.

Is this true???

[theatrus]

Yes. Don't blow directly at a bulb, just ventilate the general area.

[sir_dudeguy]

dang that was quick lol. Thanks, i thought thats what it was. It just came up in another discussion so i was wondering again.

[Steven Pro]

Could you direct me to some reference for this?

[theatrus]

Going to try digging up my sources, but the reasoning is fairly simple and is inline with the "don't touch MH bulbs, especially DE bulbs.". It can cause temperature differences between the bulb, where one part is cooler/hotter than the other. The colder/hotter parts either weaken the arc tube or cause deposits to form on the glass shortening the life. IIRC, there was a thread where someone noticed a drop in PAR from blowing a fan at a bulb.

[Steven Pro]

The reason I have always heard not to touch MH lamps is because you leave oil behind from your fingers. This allegedly can cause a hot spot and make the lamp burn out prematurely.

[theatrus]

<a href=showthread.php?s=&postid=8180599#post8180599 target=_blank>Originally posted</a> by Steven Pro
The reason I have always heard not to touch MH lamps is because you leave oil behind from your fingers. This allegedly can cause a hot spot and make the lamp burn out prematurely.

Ditto for the fan, except its a cold spot instead of hot.

[chopsuey]

<a href=showthread.php?s=&postid=8180599#post8180599 target=_blank>Originally posted</a> by Steven Pro
The reason I have always heard not to touch MH lamps is because you leave oil behind from your fingers. This allegedly can cause a hot spot and make the lamp burn out prematurely.

WOW this is news to me :eek:

I have known this to be true with halogen lights like lamps in your living room but not with Metal Halide lights. I have my MH bulbs mounted in the center of my canopy with the actual glass pointing towards each other horizontally. My fans are at both ends of the canopy blowing on the bulbs end that screws into the mogul socket.

I have never had any problems with my bulbs and have used MH bulbs for 7+ years now. Maybe my fans are far enough away from the bulbs or blowing on the mogul end is not damaging the bulb it self.. :confused: I dont know, maybe someone else can expand on this theroy, and give some more information on how far the fans need to be away from the bulb? Or exactly what damage can happen to the bulbs from the cooling of the fans.

[sage_commander]

Hmm, I think someone ought to tell the makers of all these projectors they sell for playing movies on your wall. They have a fan blowing right on the bulb. Without the fan, you probably could not even play a sitcom without the bulb burning out.

Just like with most things, heat is the enemy of performance, and I don't see how light bulbs, whether they are HIDs or not, are any different. The only problem I could see is if the lamp is already on and hot, then the fan is turned on. As long as the fan and lamp come on at the same time, it should be fine. Just MHO.

[sir_dudeguy]

My fans are at both ends of the canopy blowing on the bulbs end that screws into the mogul socket
Maybe my fans are far enough away from the bulbs or blowing on the mogul end is not damaging the bulb it self..

i think you said it right there. Blowing on the srew in part probably doesnt do anything, but having them directly on the glass part of the bulb is what cools it. And also like you say, maybe they're just far enough away.

Or exactly what damage can happen to the bulbs from the cooling of the fans.

from what i understand, its not so much "damage" as it is just making it less efficient, but not actually causing it to break or something.

Just like with most things, heat is the enemy of performance, and I don't see how light bulbs, whether they are HIDs or not, are any different.
Thats not completely true. well...you say "most" so that should be the key word...so some things its true.

But cars for example. The purpose of the cooling system is to allow it to get to opperating temperature so that it can run PROPERLY but not let it overheat. (the only reason i know this is cuz i've taken auto class at school for the last 3 years lol)

So its the same basic thing...it has to get up to the right temp to allow the bulb to work PROPERLY and push out the right amount of light/spectrum/whatever. So heat isnt nessesarilly the "enemy". Bulbs can still overheat tho, just like a car...they're made to run at certain temps (tho i know not which)

[sage_commander]

Quick OT question, sir_dude: How do you make those neat quotes show up? I stink at HTML. I don't even really know how to use those icons in the post.

"The purpose of the cooling system is to allow it to get to opperating temperature so that it can run PROPERLY but not let it overheat."

True enough, but if you watch drag racing on EPSN, you will notice how it matters whether the day is cool and somewhat humid, or hot and dry. On the cool days the cars will run better. The engine would "prefer" cooler air to be shoved into the intake. Look also at your computer. I'm not a gamer, but those that are even go so far as to install liquid cooling systems for their PC. Another example is sports. Try looking up superconductivity as well.

With the bulbs, who knows for sure. I would be interested to know how the surface temperature of the bulb affects the perfromance. I used to grow, um, tomatoes, indoors and ran a 250W HPS bulb (why aren't those used in reefs, I wonder?), and had a fan running a few inches away from the bulb, pointing right at it. My thinking is that the benefit you get from a bit longer bulb life exceeds that of losing a bit of "right now" performance.

I'd like to know how the quality control process works at the factory where they make these bulbs. How repeatable are the coating thickness meters they use to check the phosphor coating on the bulbs (or do they even use one)? If bulb A has a thicker coating than bulb B, you can bet there will be a difference in light output, whether it's the color temperature or simply the intensity of the output.

"So its the same basic thing...it has to get up to the right temp to allow the bulb to work PROPERLY and push out the right amount of light/spectrum/whatever."

I need to do some checking, but I don't think that the color temperature and the actual temperature are the same. In fact, I'm pretty sure they're not, but what I'm not sure of is if one has a significant effect on the other, in comparison to, for example, the coating thickness I mentioned above.

I suppose you could go a different route if you are interested in preventing your tank from getting heated by your lights. You could put some heatsinks of some sort on top of the canopy (but it would be a challenge to get it to not look ugly).

OK, gotta go. My family is trying to drag me away. Good night.

[sir_dudeguy]

Quick OT question, sir_dude: How do you make those neat quotes show up? I stink at HTML. I don't even really know how to use those icons in the post.


lol that?

you type this, but you dont put the spaces in between..otherwise it will just show up like it should this time i type it...

[ q u o t e ] then you enter your text in here (i just copy and paste) and then you finish with this [ / q u o t e: ]

and dont put that " : " in there at the end either. I just put that to be sure it would screw it up and not actually make it a quote.


anyways...off to my quoting :)
My thinking is that the benefit you get from a bit longer bulb life exceeds that of losing a bit of "right now" performance

losing "right now" performance wouldnt just be life span of the bulb...it would actually be the PAR/output of the bulb...in other words, possibly usefull light. I really wish that i knew a way of contacting the actuall scientist/makers of these bulbs so i can find out for sure. This has me really really thinking lol.

oh and btw..dragracing is a whole different breed of dog compaired to regular cars lol. :) But you are right on that tho.

I need to do some checking, but I don't think that the color temperature and the actual temperature are the same. In fact, I'm pretty sure they're not, but what I'm not sure of is if one has a significant effect on the other, in comparison to, for example, the coating thickness I mentioned above

they're not...for sure they're not..but i do believe they're related.
The color temp is the sectrum (or the color output in otherwords) where as the other temp is the temp in degrees... (like 200 degrees farenheit or however its spelled)
But i do believe that for a bulb to produce a certain color temp (light color) that it has to get to a hotter/cooler temp.

I've just started welding class at school..but on the gas welders, when the flame is dark orange, its only 600 degrees...when you turn it up, the color of the flame changes to bright blue/white and the temp jumps to like 6000 (i think thats the temp my teacher said..)

[drinkhomebrew]

<a href=showthread.php?s=&postid=8182078#post8182078 target=_blank>Originally posted</a> by sage_commander
Quick OT question, sir_dude: How do you make those neat quotes show up? I stink at HTML. I don't even really know how to use those icons in the post.

Use the quote button.

[sir_dudeguy]

there isnt one in the quick reply part. you have to click "post reply" for it to come up with that, and my computer always "freezes" (not gonna start debating about computeres and their temp needs now lol :) ) when i click that button

[theatrus]

Fan over entire bulb if the bulb is designed for forced air cooling (projector bulbs) = fine
Fan over parts of bulb, or fan over bulb not designed for forced air cooling = not as good

As someone stated here, I don't think it matters much at all for Mogul/SE bulbs as they have that extra glass buffer. DEs may be more problematic. But then I'm just throwing theories wildly around

[sir_dudeguy]

But then I'm just throwing theories wildly around

lol as we all are ;) But it sure is something to think about isnt it?

in any case, i would think that just in general...having airflow AROUND the vicinity of bulbs (for all you dane cook listeners ;) prolly not many as i'm probably the youngest person in on this thread lol) would be a better idea....at least safer.

[Steven Pro]

<a href=showthread.php?s=&postid=8180339#post8180339 target=_blank>Originally posted</a> by Steven Pro
Could you direct me to some reference for this? I was just wondering if this is something Sanjay or someone like him tested or simply an internet rumor. I find it hard to believe as every commercially available MH light fixture I have seen uses fans.

[sage_commander]

<a href=showthread.php?s=&postid=8182311#post8182311 target=_blank>Originally posted</a> by sir_dudeguy
lol that?

you type this, but you dont put the spaces in between..otherwise it will just show up like it should this time i type it...

[ q u o t e ] then you enter your text in here (i just copy and paste) and then you finish with this [ / q u o t e: ]

and dont put that " : " in there at the end either. I just put that to be sure it would screw it up and not actually make it a quote.


anyways...off to my quoting :)



OK. Now I get it. Thanks a lot. And here I thought I was only going to learn about reefing. But also forums in general, and even light bulbs. Heh. Yay for knowledge!

[Agu]

<a href=showthread.php?s=&postid=8180599#post8180599 target=_blank>Originally posted</a> by Steven Pro
The reason I have always heard not to touch MH lamps is because you leave oil behind from your fingers. This allegedly can cause a hot spot and make the lamp burn out prematurely.



"Caring for HID Bulbs
HID bulbs can explode if it is not handled correctly. This will occur if the bulb is very cold when first turned on, or if it contains fingerprint oils or moisture. To prevent accidents, never pick the bulb up directly by the glass - you need to be careful about fingerprints getting on it.. Handle the bulb by the base and wrap the glass body in a paper towel. Handling the bulb through the paper towel, screw it carefully into the lamp body.

If you need to clean the bulb, use a towel lightly dampened with window glass cleaner or rubbing alcohol; wipe all fingerprints, dust and impurities from bulb's glass surface. Let dry thoroughly before installing. After cleaning, always handle the glass through a paper towel. Also, make sure bulb is warmed up to room temperature before installing.

When MH bulbs are turned off they should be left to cool for 20 minutes before re-starting. Turning a Metal Halide bulb on when it is already hot severely shortens the life of the bulb and it can affect the intensity of the light. Metal Halides should be replaced after a year of heavy use."

From a hydroponics site, btw they sell fan cooled fixtures,

http://www.gchydro.com/help_lights.asp

[Agu]

Regarding flourescents, there is an optimum temp for tanning bed bulbs. I doubt it varies much for other flourescents though.

"As is generally known, a lamp can provide maximum power only if it is operated within an optimum temperature range that is approximately 108 degrees Fahrenheit. If the temperature is too low or too high, it will lead to a drop in output. To check whether the cooling system of your unit conforms to the optimal operating conditions of the lamps, the following procedure can be recommended.

During the warm-up phase of approximately 30 minutes after switching on your unit, constantly record the UVA irradiance by use of a UVA meter. The best readings will be obtained in the center of the tanning area. If the reading becomes steady at maximum UVA values, it can be assumed that the cooling of the unit is proportioned correctly.

On the other hand, if the measured values pass through a maximum before settling at a lower reading, the flow of cooling air is probably too weak. If there is a constant rise, in the readings throughout the entire warm-up phase, but without a noticeable maximum being obtained, this should be interpreted as a sign that the unit may be over-cooled. Such problems can be adjusted if the unit allows you to change the cooling air flow. If not, contact the manufacturer of the unit. "

from,

http://www.lampcompatibility.com/maintenance.html


fwiw,

[sir_dudeguy]

I find it hard to believe as every commercially available MH light fixture I have seen uses fans.

how many have you seen that blow air directly onto the bulb? All of them that i see only use exaust ones, and i've seen a few that have it like soemone earlier said...blowing around the bulb area, not on the bulb.

Agu---GREAT ARTICLES!!!

So the operating temp seems to apply to pc's too?

[Steven Pro]

I know Aquactinics uses fixtures that have one lamp blowing in and a second one blowing out. Basically, envision a small wind tunnel.

[sir_dudeguy]

on the bulb tho? or just around the bulb?

[sage_commander]

sir_dude, I hope you don't mind me straying a bit here ... :worried:

Agu, any idea why high pressure sodium (HPS) lamps are not used in reefs? If I had to guess, I would say too much red. When fully warmed up, they don't look as blue as MH lamps.

And thanks for the info, all...this forum is the bomb.

[sir_dudeguy]

sage, its all good ;)

But whats hps bulbs? just curious...

[sage_commander]

HPS (high pressure sodium) bulbs are similar to MH in that they are both considered HID (high intensity discharge) bulbs. The big advantage of these lamps is how much usable light you get per watt of power. You see both types commonly lighting parking lots and the inside of places like costco and home depot. They use a lot of power when first powering up but once that's done they are extremely efficient, much more so than flouros and incandescents.

When I first started researching this hobby I noticed that MH is overwhelmingly popular but I have yet to see anyone using HPS bulbs to light a reef. I'm not sure why that is but I know that in hydroponics and indoor gardening the MH is better for the vegetative state of growth (leaves and stalks) while HPS is better for the flowering stage of growth (where you get buds and fruit).

It's been a while since I've done any of that but I seem to remember that they are different in what part of the spectrum they reproduce the most.

[Agu]

From one of the links,

"Metal Halides
Of the two kind of HID lights, metal halides have the more balanced spectrum. They will bathe plants in light from the bluer end of the spectrum, which indicates to the plant that it's spring and time for growth. Generally speaking, Metal Halide light is used for plants which are encouraged to grow many leaves and become bushy such as lettuce, spinach, cabbage and herbs. They are also excellent for the vegetative stages of growth. They promote tight internodal spacing between branches, and help the plants to develop thick stems and large leaves which will support later fruit and flower growth.

Recent strides in lighting technology have begun to produce metal halide lamps that will reproduce a more balanced spectrum providing more of the orange/red end. The AgroSun Gold in an exemplary example of this new innovation with an amazing 49% more red light provided.

High Pressure Sodium (HPS)
High Pressure Sodiums (HPS) lamps reproduce light from the red/orange end of the spectrum, mimicking the colors of the harvest sunset. Plants use this kind of light in reproductive processes, and thus HPS bulbs help your plants to produce more fruits and flowers. At 97-150 lumens per watts, HPS light produce more lumens than a MH, but. exposing flowering plants to only a red spectrum light during the vegetative stage tends to make them stretch, lose their color and start to look downright unnatural.

HPS lights, like their MH counterparts have new bulbs which increase their less intense blue end to their spectrum. With the SunAgro (HPS) or the Hortilux, you can get a 25-30% increase in the blue end of the light spectrum. These lamps will produce more natural compact growth."



In the aquarium hobby lighting has another issue, we're concerned with the aesthetics of the light. I'm sure corals could be grown just fine under lower color temp (more of the red/orange spectrum) lights. However corals will tend to not be as colorful and the water will look yellow. At one time I used 400w Iwasaki 6500K bulbs (which is considered the minimum color temp for reefkeeping), I was known as the guy with the big ugly corals ;). MH in the blue spectrums make the colors more vivid and the water appears clearer.

[sage_commander]

<a href=showthread.php?s=&postid=8193551#post8193551 target=_blank>Originally posted</a> by Agu
In the aquarium hobby lighting has another issue, we're concerned with the aesthetics of the light. I'm sure corals could be grown just fine under lower color temp (more of the red/orange spectrum) lights. However corals will tend to not be as colorful and the water will look yellow.

That makes sense, Agu. I figured that HPS was just as good at punching through the water column as MH, but you just don't see them anywhere. Because it basically would look ugly is a straightforward answer. Occam's Razor, I guess. :)

[cdentii1]

Solaris lighting system hummm......
this may be the best thing since MH came out check out this link
http://www.advancedaquarist.com/2006/8/review2/view?searchterm=metal%20halide%20heat
very expensive though but cheep in the long run.

[Rockhead21564]

Great info everyone, love learning. Another thing that can (and does, I KNOW) happen is breaking the bulb. When purchasing a cheaper MH bulb you tend to get a much thinner glass dome. When the fan hits the bulb, it cools it substanitly(sic). At the same time the internals of the bulb are heating, thus begins the death of your $50 MH bulb. Just some first hand experience, lol.

[sir_dudeguy]

Solaris lighting system hummm......
this may be the best thing since MH came out check out this link
http://www.advancedaquarist.com/200...20halide%20heat
very expensive though but cheep in the long run.



we just had a thread about this like 4 days ago lol. (ok maybe a week or so) But we all calculated out the costs of the setup initially and to run per year. And the bulbs on that last 11 years (if the bulbs reach full life expectancy). So after calculating out all the costs and then compaired it to 11 years of mh of 250 watts (thats what the solaris one that we compaired was equal to) ....the solaris came out to be quite a bit cheaper.

[cdentii1]

<a href=showthread.php?s=&postid=8196248#post8196248 target=_blank>Originally posted</a> by sir_dudeguy
we just had a thread about this like 4 days ago lol. (ok maybe a week or so) But we all calculated out the costs of the setup initially and to run per year. And the bulbs on that last 11 years (if the bulbs reach full life expectancy). So after calculating out all the costs and then compaired it to 11 years of mh of 250 watts (thats what the solaris one that we compaired was equal to) ....the solaris came out to be quite a bit cheaper.

The story of my life:
A day late and a dollar short.
or in my case about $3000.
LOL...........

[chopsuey]

I hate to dig this topic back up but here is a pic of what my setup looks like on either end of my canopy. I just wanted your opinions as to whether my fan setup looks safe for my 400w MH SE bulbs.

http://www.isosquad.com/tank/mhsefan.jpg

[sage_commander]

Is that fan blowing on the bulb or sucking air out of the capopy? From reading this thread I think you would want the latter. Simple enough if it's not - just unbolt that fan and turn it around.

[sir_dudeguy]

yeah i agree w/sage

[cdentii1]

Ok soo let me get this straight it is better to suck then blow.....
uummmm the air that is right?
I hope my wife reads this forum. LOL

[sir_dudeguy]

well imo, you need both...but just no air blowing right on the bulb. Make it blow underneith the bulb, and imo, at the water is better. Cuz then you get the evap which cools

[Steven Pro]

Has anyone found a reference for fans lowering the PAR of a lamp yet?