see this:
http://www.photo.net/photo/edscott/h2o.jpg

more water depth more blue (higher temperatures) .

taken from he

http://www.photo.net/photo/edscott/cf000030.htm


"LeighMo" wrote in message
...
Only anecdotal, I'm afraid. I've been talking to many people over the
years
about lighting. An often quoted opinion is that "anything above 6000 K
will
encourage algae."

I've heard that "blue light causes algae" thing, too. That's the main
knock
against actinics.

But it hasn't been a problem for me. I've tried different color bulbs,
and
find I like 10,000K daylight best (so far). Just because I like the
"white"
look of the light. I haven't noticed any difference in algae. However, I
have
noticed that plants seem to grow taller with the 8800K than with the
10000K. I
suppose that makes sense. The 10,000K are meant to simulate light at the
water's surface, while the 8800K are meant to simulate light a few feet
below
the surface. The 8800K makes the plant "think" it's deeper.


Leigh

http://www.fortunecity.com/lavender/halloween/881/