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Re: Electric Lamps
You wrote:
>
>
>Aquatic Plants Digest Tuesday, 27 June 1995 Volume 01 : Number
150
>
>In this issue:
>
> Surface Sterilisation
> Electric Lamps (a brief history since Edison)
> [none]
> "Hot Gravel" - another alternative to substrate coils?
>
>See the end of the digest for information on subscribing to the
>Aquatic Plants mailing list and on how to retrieve back issues.
Martin Harriman wrote:
>From: martin-h at mail_utexas.edu (Martin Harriman)
>Date: Tue, 27 Jun 1995 04:56:09 -0500
>Subject: Electric Lamps (a brief history since Edison)
>
>Here's a very brief rundown on lamp types for the curious:
>
>Electric lamps can be divided into incandescent (conventional and
>quartz-halogen) and discharge. Incandescent lamps (of either variety) put
>most of their energy out in the infrared, and so are of little interest
>here (think of them as tiny expensive electric space heaters that happen to
>light up).
Snip...
Whoa! The rest of this posting was superb, and I thank you for it.
Unfortunately, I must quibble with the above statement. Like incandescent
lamps, the sun is a hot incandescent source, and the best imitator we have
of sunlight is plain old halogen lamps! [I admit the heat often must be
vented]
Plants LIKE deep red light, with their main absorption peak at 670nm and a
weaker one in the violet at about 450 nm. An equivalent blackbody at
2800-3000K is just about right. Most of the gas discharge lamps put out a
line here and a line there, with little regard for the plants' needs. "Cool"
and "Warm" flourescents have gobs of green, right in the chlorophyl
absorption dip, and almost none where plants need it (red and violet). It
makes them "look" bright (i.e., have high Lumens) but they are terrible
plant bulbs, compared to "Daylight" or Chroma 50s. A broad-band incandescent
source is of great interest here, and I have several tanks whose plants can
prove it.
Last December, I reported on the compact-base screw-in flourescents made by
LOA and GE that used tri-phosphors. They have been terrific for plants, too,
but my local stores are now only carrying an inferior brand that uses the
nearly worthless green-rich phosphors. Reliability has been superb, with
only one infant mortality (happily replaced by Home Depot). For highly
illuminated small aquaria, they are very hard to beat.
I hope my one tiny quibble does not detract from an otherwise wonderful
posting. The reef folks have gotten us so off into duplicating skylight that
we sometimes forget the sources our FW plants need.
Wright