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Re: [APD] lightning -- or - Give me that ol' time relighting

All light bulbs, incandescent, fluorescent, MH, etc. get
dimmer as they age. But one needn't replace bulbs every six

It used to be so but it's not really true for wet gardeners
anymore. Why?

VHOs (Very High Output fluorescent bulbs) and MHs might
need to be changed that often -- VHOs run at rated amperage
get hot and spoil the phosphors and MHs (the older ones
anyway) tend to shift spectrum quickly.

But HO (High Output fluoresecent bulbs) like Power Compacts
and T5s will be down only about 80% after two years or more
and won't lose more than another 5% over their entire life.
Most of the loss occurs in the first few months, first
thousand hours of burning -- the rate of loss is slower
over time. So brand new bulbs look brighter than almost new
bulbs but one year bulbs don't look much diff from 2 year
bulbs, etc. Most PCs or T5s should be at about 80% of
maximum output by the time they die through normal use (or
the rated average life).  Changing them every six months is
like totally radical, man. 

Of course output and aging vary by bulb model, maker and
the match between the bulb and the ballast. But you should
be able to count the age in years, not months.

Anyway, probably more people suffer from "too much" light
than from "too little." We've come a long way in the last
few years. Certainly a long way from, say, George Booth's
time (hee heee heee)  ;-) .

Which reminds me to suggest: When planning a tank, plan a
lighting setup that will work well over 90% of the bulb's
life rather than just a few months or half a year.  

good luck, good fun,
Scott H.

PS: GB actually recommends about 2 wpg
(PC-with-AHS-reflector or equivalent) as a safe and sane
lighting level for most situations and there's nothing old
fashioned about that!

--- revance at indiana_edu wrote:
> Quoting Roeland Grommen <roeland_grommen at UGent.be>:

> > . . .The fluorescent tubes (2 x 30 W) above my 60 liter
> > aquarium are about 2
> > years old and it is about time to change them. . . .
> > Best regards,
> > Roeland
> > 
> What will probably help your growth most is changing the
> bulbs more often. 
> Fluorescent bulbs will burn for years, but their
> intensity drops drastically 
> over time. Even though you can't tell the difference, the
> plants can. Most 
> people recommend changing bulbs every 6 months, IMO you
> can push them a little 
> longer (and probably will by accident... kind of like an
> oil change). As for 
> the difference between those two bulbs, I have never used
> either. I imagine 
> you will probably notice a big difference despite which
> one you use just 
> because you will have a fresh bulb. If the one is less
> expensive and will 
> allow you to change the lamps more often, I would use
> that one. If you buy one 
> that is so expensive that you try to use it forever to
> "get your moneys 
> worth", it will probably do more harm than good.

-  -   -   -   -   -   -   -
AGA 2004 Annual Convention
Designing The Nature Aquarium -- demonstrated by Takashi Amano
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