Mogal Metal Halide bulb direction

I have my bulbs facing longways in the tank. I remember reading a while back that the light will shine better on the bottom of the tank if they are running front to back. Anyone ever heard this before?

 

I don't see how that would make any difference whatsoever. The depth of travel and spread is up to the reflector that you have. Rotating it 180 will not change it's characteristics. Not that I know of anyhow.

Now.... Rotation of the bulb makes a huge difference. IE.. nipple up, down or to the side.

 

I'm talking about 90 degrees so if you are looking at the tank they will be | instead of -

 

Absolutely correct. It's all in the reflector. A good quality reflector will mean all the difference. Unfortunately the average person will always look to save a buck on the reflector when it is really the most important piece of the puzzle.

 

Right, it depends on the reflector. If your using a spider/parabolic reflector, then the reflector and bulb should be perpendicular to the front of the tank. if this isn't a requirement for your reflector, then it don't matter.

 

I heard about that nipple or air passage before. IS that true? If I keep the nipples on both the same(dead top center) the inside of the bulbs are different angles.. whats more important. Can someone explain this better?

 

yes, should be between 10 and 2. Something to do with the spacing, burns too hot or something if too tight. Had a discussion with an XM rep, don't remember the exact reason, but can attest it can make a big difference!

 

I was reading that that "path" or air bubble lets the lamp breath.

 

This is what I am talking about. And YES, it makes a huge difference. Each bulb by each manufacturer will be effected by orientation in different ways. You will see life, color, and PAR effected. It is a push pull effect. If PAR goes up, life will decrease.

Either way, you can choose to fine tune your bulbs adjusting the orientation. Somewhere on the interweb is a good spreadsheet on the effects on different bulbs. I will try to hunt it down and link it. I want to say it was Sanji who did all the dirty work.

The nipple is part of the bulbs manufacturing process. It does not allow gas to pass through it. If this was the case, DE Double Ended bulbs could not function, as they have no outer protective casing.

 

Can't seem to find the spreadsheet. Here is a good link that I like to refer people to on the subject.

Product Review: Nipple Orientation of Metal Halide Bulbs Revisited | Advanced Aquarist's Online Magazine