Re: uv rays

["Bill Wichers" <billw at waveform_net>]

>I have my red mangrove swamp set up (third tank, much to my wife's
>chagrin!).
>I'm using the HPS light over it with no protective cover (until I build a
>custom hood this spring). Are the light rays from a HPS harmful to the eye?

I'm not aware of any serious UV emissions from HPS lights, MH is more of a 
problem in that regard and there the outer envelope of the bulb is normally 
made with a UV inhibiting glass to preven UV transmission. The big problem 
with a non-covered HID (High Intensity Discharge, which includes HPS, MH, 
MV, and other arc lights) is that because the bulb operates at very high 
temperatures, and water splashed on the bulb will likely cause the bulb to 
shatter. It would probably be a good idea to at least put a piece of 
hardware store bought glass between the light fixture and the tank to be 
sure no water hits the bulb. 

I've lost bulbs from splashing in greenhouses like this. HID bulbs break 
*violently* when hit with water. The don't blow pieces out like a bomb, but 
they are loud and they do produce a lot of very sharp glass shards that are 
difficult to see due to the thinness of the glass. 

>Travis
>10-degrees this morning. Pig's water was frozen. 18-20 inches of snow on
>ground.

    -Bill
with about 3" of snow on the ground that is melting now, and *very* thick 
fog everywhere. 

*****************************
Waveform Technology
UNIX Systems Administrator