How often...

GSM · 06-09-2002, 10:53 AM

must a 20k DE bulb be swapped out for a new one? Seems I can't get a definitive answer... Some say 6 months, some say a year... I hope it's the latter!

Doug1 · 06-09-2002, 11:33 AM

The higher Kelvin bulbs allegedly undergo spectoral shift sooner than say the Iwasaki 6500K bulbs, and theres not an easy way to test for this. One could get a lux meter and take readings when new, and after the appropraite burn in time, then monitor monthly, thereafter. I would think that when the output falls off say 30% its time. Hopefully at least a year.
Bill E uses HQI, and has for at least a year now, perhaps he will comment on life span

GSM · 06-09-2002, 12:15 PM

Doug, thanks! How much does a decent lux meter run? Sounds expensive, heh.

Doug1 · 06-09-2002, 12:39 PM

I have seen several people refer to one they got at HarborFreight, seems like they were around $30. I just searched their websight 47 ways from sunday and don't see them listed anywhere

Maybe Radio Shack or one of the scientific supply sites may have them