A friend of mine got me thinking. The 6" fan I attached to my HID reflector is making noise so I decided to replace it.
I put the fan there years ago to draw the hot air away from the bulb and out of the hood. My friend says big mistake. HID lights are designed to run hot, and pulling hot air away will cause them to lose their efficacy.
Ive added a photo as reference.
Any thoughts?
I use LED lights. But Amazon!
HID lights do run hot. That is what the hood is for so you can connect a fan and draw the heat away. That way you can put the light closer to the plant to make them more efficient.
This is my understanding anyway.
I’ve never heard of that, just that the glass cuts down the light in the 10% range or so.
I bought an HID kit once, it came with a 4" blower type fan that pushed the air through instead of pulling. It worked great. Maybe there’s some heat shortening the life of that fan.
Look at HID cool tubes. I’m guessing that the other end of yours is open like a cool tube. If you need it, then I probably wouldn’t go with an axial fan as they don’t like restrictions. Would rather have a true centrifugal or maybe a hybrid centrifugal/axial there, depending on the requirements.
Also I noticed it looks like that lamp diffuser is frosted, which will knock it down a lot more beyond clear glass.
I just looked at my photos and I can’t see my a frosted diffuser anywhere? You must be looking at something else.
Anyway, appreciate the advice.
BTW my diffuser is clear glass.
Would be my choice for sure.
@Beard-O I use a 10 inch for my 2 x 8 inch hoods in an 11x14 room.
600 w x 2. 
Lil further away from the main heat with the wall mount.
Keeps my temps in line at 75-80 f when lights are on.
5 th year with no issues. Tho it is a bit pricy near 300$. 
Thanks. That’s more or less what I’m doing, except I’m using a 4x4 tent.
Optical confusion, the back of the housing (or whatever it is) in the pic looked like white glass to me.
The bulb can run fine in a hood with glass or a open wing style. Look at alot of old streetlights, back in the day of course, that were hps style lamps on the poles. They lasted a long time…trust me ive changed them out from 400w up to 1500w stadium lights. They were all enclosed.
