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Re: [APD] Power Compact Bulb Useful Life: 12 months max

Just a reminder: one can be fooled with new fluorescent
bulbs.  The more time the bulbs have been burning, the more
slowly the output degrades.  The first few hundred hours
can give a roughly 10% drop, and the next 10% takes a year
or two.  It doesn't really go in sudden steps; it's a
curve. MSome manufacturers rate the light output of their
bulbs after the initial burn-in period. This gives a lower
rating but results in a smaller percentage decrease one or
two years out.

New bulbs will almost always outshine old bulbs -- even
slightly old bulbs.

Which is not to say that your plants aren't happier getting
more light. But folks have used PCs for 2 years and more
and grown palnts nicely.

I think Tom Barr has a standing offer to accept anyone's
PCs if they are only a year or so old. I don't know if
he'll want the 2-year olds you have ;-)

Scott H.
--- Dave Millman <dave at tactics_com> wrote:
> My tank looked great for the first year. I sold lots of
> plants at the LFS 
> and gave them away online, everybody was happy.
> The tank went steadily down hill during year two. The
> only good thing about 
> that year was that I continuously improved all of my
> nutrient and 
> cultivation techniques so that I'm doing everything
> pretty much perfectly 
> now (50% weekly water change, Tom Barr's estimative index
> method). But the 
> tank was still pure greenwater for months 22-23. Daphnia
> helped, but it was 
> too much of a pain to keep them in the tank.
> So I borrowed a UV filter to clear the tank, and followed
> Tom Barr's advice 
> to start at the beginning: Light.
> I bought four new 55W bulbs from AH Supply to replace my
> 23 month old ones. 
> Guess what: Using the light meter in a professional video
> camera, I 
> discovered that the difference in brightness between the
> new and old bulbs 
> was much more than one f-stop. This means the old bulbs
> were putting out 
> less than half the light the new ones were, at least in
> the frequencies to 
> which the light meter is sensitive. While this imprecise
> test ignores the 
> plant's spectral requirements, it still says to me that
> my tank went from 
> over 3W per gallon to under 2W per gallon, while I was
> still dumping full 
> nutrients in there. No wonder I had green water.
> Now the new bulbs are in, and the plants are pearling
> like mad. I haven't 
> seen that in nearly a year.
> If anyone out there has the expertise and equipment to
> properly measure the 
> output of my old bulbs, I would be happy to send them to
> you if you will 
> publish a comparison with new bulbs. AHS or another
> vendor might even 
> contribute a new bulb for comparison.
> I can't imagine why somebody would spend premium money
> for a CF fixture, 
> then not replace the bulbs every 12 months.

See you in Dallas at the Aquatic Gardeners Associaton
2003 Annual Convention
Nov 14-16
S. Hieber

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