Re: lumen loss

>Greg. Tong says:
>I can't help thinking that it's either the aquarium lamps,  something in
>the fixture, or, as Karen suggested, the way we use aquarium lights that is
>shortening their life.

I vote for all three!

According to the Valmont Ballast technical guide, short lamp life (which may
be different than reduced lumens) is attributed to:
1) Improper voltage
2)Improper wiring
3) Poor lamp to lamp holder contact
4) Extremely short dury cycles (many lamp starts per day)
5) defective starters (applies only to preheat)
6)Defective lamps
7)Improper ballast application
8)Defective ballast

Number 6 and 7 seem like possible candidates to me. First, I doubt that
specialy aquarium bulbs or ballasts made for aquarium application are
produced with the same quality control as other commercial lighting.
Improper matching of bulbs and ballasts may also be a contributing factor. I
suspect that most people randomly combine a ballast with a lamp. I use both
shop lights with grounded enclosures and custom hoods without grounding. I
would think that lighting engineers might match a particular ballast to a
type of bulb for optimum use. :) There are electronic, conventional magnetic
and hybrid ballasts. There are T-12 and T-8 bulbs; instant start, rapid
start and pre-heat.  Which combination do you use. I know that I don't know. <g>