Metal Halide without glass covering-UV rays

islandcreation · 02/07/2008, 03:21 PM

I was reading Anthony Calfo's new book and he talked about UV rays from halides. Can anyone tell me how much of a reduction does a piece of glass will have on a 250 halide? I used to have a glass piece on my frag tank which is only 6 inches in depth with the light 2 feet over it. I took the glass of actually it broke when I was making a new stand whne moving it. So now my zoas/palys aren't looking so good now. Some seems fine and the other not so good. Previously everything was doing well. Any thoughts?

cbrguy · 02/07/2008, 04:43 PM

Is the bulb a HQI? they are the only ones that need the glass. If it is you have to put a piece of glass on it again. It will kill everthing. It will give you a sunburn too!

fade2black · 02/07/2008, 04:44 PM

Why not just replace the bulb? If I am reading this correctly, you broke the outer part of the bulb? Is this a SE or DE bulb?

The Grim Reefer · 02/07/2008, 05:17 PM

If you broke the glass UV Shield you do need to replace it. Just have a piece of tempered glass cut to size.

islandcreation · 02/07/2008, 08:15 PM

Its a single end halide bulb. I thought you didn't need a glass cover for SE bulbs? How much UV does a tempered glass or a glass in general reduces? Thanks

This is the glass piece that just shields the bulb. Not the bulbs glass itself.

DarG · 02/07/2008, 08:22 PM

I did the math for DE bulbs and it is just under 20%. But it would depend some on the thickness and type of glass.

You dont need it for SE bulbs.

The Grim Reefer · 02/07/2008, 08:51 PM

Yeah, if it single ended you don't need the glass, it cuts out about 20% of the light

pjf · 02/07/2008, 08:59 PM

The reef lighting website will produce a spectral plot of your lamp: http://www.reeflightinginfo.arvixe.com/

If it is a DE lamp, you will be able to select the spectral plot with or without shielding to compute the amount filtered. Shielding of DE lamps is necessary for safety & health otherwise UV-B & UV-C will literally fry your tank.

If it is a SE lamp, the built-in glass envelopes alone should provide UV shielding but I guess that depends on the lamp. Personally, I would take The Grim Reefer's suggestion and replace the broken tempered glass shield.

If you wish to check, purchase one of these Oregon Scientific Personal UV Sensors from Target ($20):

02/07/2008, 03:21 PM	#1
islandcreation Moved On Join Date: Feb 2006 Location: NorCal Posts: 412	Metal Halide without glass covering-UV rays I was reading Anthony Calfo's new book and he talked about UV rays from halides. Can anyone tell me how much of a reduction does a piece of glass will have on a 250 halide? I used to have a glass piece on my frag tank which is only 6 inches in depth with the light 2 feet over it. I took the glass of actually it broke when I was making a new stand whne moving it. So now my zoas/palys aren't looking so good now. Some seems fine and the other not so good. Previously everything was doing well. Any thoughts?

02/07/2008, 05:17 PM	#4
The Grim Reefer Ready for some NOBALL!!! Join Date: Sep 2003 Location: Kingman Az Posts: 25,259	If you broke the glass UV Shield you do need to replace it. Just have a piece of tempered glass cut to size. __________________ America, the way it outta be! Current Tank Info: 120 Starphire with Illudium Q-288 Photon Regurgitator DIY LED lighting

02/07/2008, 08:51 PM	#7
The Grim Reefer Ready for some NOBALL!!! Join Date: Sep 2003 Location: Kingman Az Posts: 25,259	Yeah, if it single ended you don't need the glass, it cuts out about 20% of the light __________________ America, the way it outta be! Current Tank Info: 120 Starphire with Illudium Q-288 Photon Regurgitator DIY LED lighting

02/07/2008, 04:43 PM	#2
cbrguy Registered Member Join Date: May 2004 Location: Downingtown, PA Posts: 493	Is the bulb a HQI? they are the only ones that need the glass. If it is you have to put a piece of glass on it again. It will kill everthing. It will give you a sunburn too!

02/07/2008, 04:44 PM	#3
fade2black Premium Member Join Date: Oct 1999 Location: Mentor, Ohio Posts: 1,358	Why not just replace the bulb? If I am reading this correctly, you broke the outer part of the bulb? Is this a SE or DE bulb?

02/07/2008, 08:15 PM	#5
islandcreation Moved On Join Date: Feb 2006 Location: NorCal Posts: 412	Its a single end halide bulb. I thought you didn't need a glass cover for SE bulbs? How much UV does a tempered glass or a glass in general reduces? Thanks This is the glass piece that just shields the bulb. Not the bulbs glass itself.

02/07/2008, 08:22 PM	#6
DarG Registered Member Join Date: Dec 2006 Posts: 5,515	I did the math for DE bulbs and it is just under 20%. But it would depend some on the thickness and type of glass. You dont need it for SE bulbs.

02/07/2008, 08:59 PM	#8
pjf Premium Member Join Date: May 2005 Location: Colorado Posts: 2,954	The reef lighting website will produce a spectral plot of your lamp: http://www.reeflightinginfo.arvixe.com/ If it is a DE lamp, you will be able to select the spectral plot with or without shielding to compute the amount filtered. Shielding of DE lamps is necessary for safety & health otherwise UV-B & UV-C will literally fry your tank. If it is a SE lamp, the built-in glass envelopes alone should provide UV shielding but I guess that depends on the lamp. Personally, I would take The Grim Reefer's suggestion and replace the broken tempered glass shield. If you wish to check, purchase one of these Oregon Scientific Personal UV Sensors from Target ($20):