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Re: [APD] low light

During our past summer (January) I made some trials with a luxometer and an 
adaptation I made over a incandescent lamps pendant. I made a chassis to fix 
in it, and I installed two HQI 70w lamps to see how they behave. I had some 
interesting results, since I could blend two different brand and/or color 
lamps, with different activity cycles.

I also find what was obvious: light was emitted in privileged directions, 
generating patterns and lobes, always with the omnipresent distance to the 
lamp. These patterns changed even using different lamps.

So there are many factors IMO to take in account if a rule of thumb want to 
be emphasized.

I recall some basic inputs for solving an illumination problem:

- Shape and dimensions of the room, wall and ceiling reflection factor, 
which derives in a space factor.
- Type of device chosen, which give has an illumination pattern and 
coefficient, which also considered age and dust over the lamps.
- Illumination level, working plane, position of illumination devices.
- With all these you can have the number of devices to install.

There are a few Electric Engineer associations, which study these subjects. 
Our problem has some points of intersection with them.


>From: Jerry Baker <jerry at bakerweb_biz>
>Reply-To: aquatic plants digest <aquatic-plants at actwin_com>
>To: aquatic plants digest <aquatic-plants at actwin_com>
>Subject: Re: [APD] low light
>Date: Sun, 18 Sep 2005 11:16:21 -0700
>Thomas Barr wrote:
> > So all those folks counting watts, lumens, little physicists, might want 
>to focus on good CO2/nutrients routines learned at high light, and applying 
>them to low/er light.
>Does taking jabs at people make your plants grow better?
>Most people don't care about the nitty-gritty details, and that's
>absolutely fine. You appear to be one of them. What I don't understand
>is why you are belittling the idea that hypotheses should be tested
>before being represented as fact.
>Growing plant X under Y lights doesn't tell us anything useful without
>further information. The only way to find out what is relevant and what
>isn't is with controlled studies, or at least semi-controlled. The last
>thing I would have expected to hear on this list is somebody discounting
>that idea.
>Jerry Baker
>Aquatic-Plants mailing list
>Aquatic-Plants at actwin_com

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