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Re:natural light intensity

<Date: Sat, 01 Nov 1997 21:54:50 -0800
<From: Stephen Pushak <teban at powersonic_bc.ca>
<Subject: natural light intensity


<How feasible is it to use natural light (no sunlight) to
light an
<aquatic plant tank? I have a hunch that its important to
get about a
<half an hour to an hour of sunlight.

At 49 degree north  (Vancouver BC, Canada)latitude the light
intensity in the winter is about 1/10th of the rate in the
summer. So you certainly need additional light, also because
day length after September 21 is less than 12 hours.

<Also, how much does this light intensity vary according to
a cloudy day
<and a rainy, overcast day?

The light intensity will drop considerably during cloudy or
rainy days.

<The place we're interested in is Cebu City in the
Philippines. The idea
<is to see how feasible it is to use ambient lighting since
the cost of
<electricity is relatively high and sunshine is virtually

Variation in light intensity is much less in near the
equator as towards the north and south pool. Light intensity
and daylength in the tropics are optimal for growing
aquarium plants outdoors, although I suspect that you need
some shading.

<How about the idea of placing the tank where it would get
<sunlight for a period of half an hour or more? I read
stories in TAG
<about early aquatic plant pioneers favoring east facing
windows. I
<expect it was even more of a trial and error process for
them than for
<us today! ;-)

Placing aquariums near east facing windows is a option, but
variation in light intensity and daylength to much at 49th
north latitude (Vancouver BC). Artificial light is much more

Jos Liem
New Westminster BC