MH Nipple Orientation

[NaH2O]

I recently took the time to read a couple of articles from a few years ago by Richard Harker on nipple orientation of MH bulbs. Some hobbyists note a difference in the appearance of the bulb color when the nipple is orientated down or other position than straight up. According to the research conducted by Harker, he was unable to recreate the color shift, or a difference enough that would be visible. What do you think about this argument? Also, the argument that nipple orientation has little to do with a bulb's performance with color and intensity? Were the methods of experiment bad?

How does one explain the anecdotal observations such as bulbs failing to fire if the nipple is mis-positioned? First, a reef tank is a hostile environment for any electrical device, particularly one that draws a great deal of current. Corrosion can build up in the contacts and sockets of metal halide lighting. In the course of trying to reorient the nipple of a metal halide bulb, one must remove the bulb and by doing so may remove the corrosion that was preventing the bulb from firing. I have found that with an older metal halide bulb, simply unscrewing and screwing the bulb back in will enable the bulb to fire. Those who have observed a color shift when changing the orientation of the nipple may also be inadvertently cleaning the corrosion from the bulb contacts while attempting to reorient the bulb. There is a very small color temperature shift at different points around the bulb. It is possible that the small color temperature difference is more apparent when the bulb is placed next to a second bulb with a different color temperature. This would be most apparent as a bulb ages and shifts in color. In these experiments I was unable to significantly shift the color temperature of any bulb by rotating the position, but I have observed color shifts in older unstable metal halide bulbs where the arc periodically changes position. One should realize, however, that the nipple has nothing to do with the position of the arc within the envelope, and that the nipple has nothing to do with color shift.

Here are the 2 articles:

Nipple Nonsense
Nipple Orientation of Metal Halide Bulbs Revisitied

Example of anectodal evidence (quotes from another thread). Do you think that the color shift Mike notes below is really from "cleaning the corrosion from the bulb contacts while attempting to reorient the bulb" as stated in the quote above? I don't think so, so how does that explain what Harker found in his research?

Try them both ways Min and see what comes of it. I have down that with ushios, iwasakis and radiums and thier is a big shift in color when the nipples are pointing down. On the ushios and iwasakis went yellow, radium darker blue.
Mike

I have done it for a few reefer to watch, Basically the color of the bulb was whiter, I then turned the bulbs off waited for them to cool and then turned the nipple down. When they re-lite you could see the color difference, they turned yellow. I have done it side by side with the same temp bulb to show it.
Mike

 

[Woodstock]

Interesting. I have always heard that the nipples should point upwards. As far as the experiment, there are many variables involved (type of bulb, age of bulb, the ballast used, the reflector used..blah, blah) so it would be incorrect to test one bulb and then state that ALL nipples should be one way or another. It is certainly worth the extra effort to try your current bulb both ways just to see how it affects the color. When I get home, I will do just that with my new Sun Aquatics

 

[NaH2O]

I don't think ballast would effect the results of what was being tested, as the differences around the bulb was being looked at.....so the difference in intensity and color from one side of the bulb to the other. Harker did test a variety of bulbs, and in the second study included bulbs of various burn hours sent from hobbyists. He did note in the second study that it seems the support wire was a better predictor of the bulb orientation producing more light. Since the anecdotal evidence seemed to center more around the German 10K bulbs, the second study was conducted on those bulbs.

If a bulb is more intense on one side than the other.....what would be better.....to have the higher intensity pointing up towards the reflector (and being reflected down), or point the higher intensity down towards the tank?

 

[mojoreef]

Hmmm funny how this thread has attracted female members??? lol


Mike

 

[NaH2O]

Hmmm funny how this thread has attracted female members??? lol


Mike

It will be real funny in a little while......where's that PM button

 

[kevinpo]

Hmmm funny how this thread has attracted female members

Easy there big fella :badgrin:

I have tested several brands or 400W SE bulbs and some of them change color drastically when the inner envelope nipple is pointed down. Up or side to side I was unable to tell any difference. Another thing that can happen after using the bulb for a while is that the halides/carbon that condense each time the bulb goes off can collect in the nipple tip and not totally vaporize upon ignition. This can cause a darkening/shadow effect when the bulb is lit as it ages.

Regards,
Kevin

 

[Woodstock]

Easy there big fella :badgrin:

I have tested several brands or 400W SE bulbs and some of them change color drastically when the inner envelope nipple is pointed down. ....

Drastically as in bad or good?

 

[mojoreef]

As in bad.


Mike

 

[kevinpo]

Usually they appear dim and either more yellow or more blue than they should depending on the bulb.

Regards,
Kevin

 

[aquariumdebacle]

my nipples point out

 

[DlBerlin]

LOL!
I had some of the "plus" brand Ebay bulbs. One was VERY green and the other much whiter. I had heard rumors of the "nipple theory" and turned the one that was green to the same orientation as the whiter bulb. Worked for me-both were white then.I honestly cant remember(cant remember anything anymore) which direction they were pointing.

 

[jlehigh]

A part of me wants to attribute some of this to the persons eyes. When I come in from a sunny day my tank looks bluer than Poppa Smurf (not Mojo but the real poppa smurf ). If I go into the garage and look even slightly in the direction of my 20K XM then go back inside and look in the tank my 400W 20K DE's look like 10K's!

This could also be attributed to Wine and beer intake but my eyes have always made a bigger difference than my bulbs orientation..

 

[Boomer]

Kevin what kind or bulbs are these as in orientation,V, H or U

 

[WaterDogs]

I think both nipples pointing up looks best. :lol:

 

[NaH2O]

Kevin what kind or bulbs are these as in orientation,V, H or U

Boomer can you elaborate on this a bit? V? H? U?

If there is a big difference in the colors folks see, then why would Harker have such differing results? He says in the second experiment that the color differences would be too slight to be visible. Is there something wrong with the way the experiment was set-up?

 

[Boomer]

Is there something wrong with the way the experiment was set-up?

I do not want to eat on Kev but would bet on it, as Richard is an expert at this as is Sanjay

Bulb Mounting Positions, where bulb must be mounted in this position

V= Vertical mounted bulb

H = Horizontal

U = Universal (any position, V or H)

The curvature of the plasma arch tubes are not the same

 

[Kensn]

Might of been vertical , horizontal and up Nikki.

 

[Katchupoy]

Im no scientist, but I too experience a big color shift on my bulbs when point differently other thatn 12:00 .

BTW, Im talking about SE bulbs on magnetic and electronic ballast.

 

[kevinpo]

Most bulbs for the aquarium hobby today are Universal but are no longer designated (printed on the bulb) as such. The old Ushio bulbs that I owned had the U designation printed on the bulb in the part number. I ran them in the horizontal position and there was a big difference in the coloration between the two bulbs running side by side according to the nipple orientation. The change was quite repeatable. I haven't tried it in a few years as I always install new bulbs in any postion except with the nipple down nowdays. I can't explain why Richard got different results. I may have some of the old Ushios lying around. If I get some time I may play with them and see how they look.

Regards,
Kevin

 

[kevinpo]

I also remember a thread on RC where someone had posted pictures of the bulbs burning side by side one with the nipple pointed down and the other up.There was quite a noticeable difference between the two. Then when they turned the bulb they looked the same.

Regards,
Kevin