Ok, I attended a Reef club meeting one day in ATlanta. Their topic was
algae growth and how to eliminate or reduce it. They stated actinics
wave lengths do not support the growth of algae (green type) and by
placing the actinic bulb closest tot he front will reduce its growth,
and in regards to light shining in the tank from outside, the
wavelengths produced by actinics is enough to counter or dilute its
direct affect...that is unless its direct sunlight. I sure am not a
physics guru by any means, but to me and the others it all sounded
logical. Even the local LFS here all place their actinics closest to
the front glass,.....It has something to do with the wavelength and
color produced by actinics in regards to supporting green growth.,
Actinics do not do very well if used in a light over a fuge.....nor in
freshwater planted tanks, even the 50/50 do not do all that great as
compared to a 6500 or 10k light when it comes to green stuff.

Wavelength / is critical from what I understand to proper or improper
growth, and as bulbs age they can create problems, and a old bulb even
though it may appear bright and good to the naked eye can readily
promote algae.

On Wed, 15 Feb 2006 16:32:12 -0600, "Pszemol"
wrote:
"~Roy~" wrote in message ...
I know as well as you do, that algae has to have a source of nutrients
to thrive, and also that a new tank can have algae initially. I
assume you have checked your source of water for any "hitch hiker"
sources of nutrition in the line of phosphates and nitrates, right?

Miskairal has no reason for searching phosphate sources in his
water if he used the same water for two salt mixes and one is not
detecting phosphates but other does. Conclusion is quite simple:
salt mix contains phosphates...

Unless the water used in both tests is different, of course.

If yu have actinics separate from the other bulbs, place the actinic
bulb closest to the glass and its been proven to help keep algae under
control......as the nm rateng of actinics will not promote algae
growth, and sort of block any outside light to some degree from
infiltrating the tank.

????
Could you please expand little more on the above ?

First: algae uses red and blue rays of light for photosyntesis.
Actinics look like a perfect source of high energy for algae.

Second: how do you imagine shining on the glass with a light
source could block the other light sources from entering the tank ?

My understanding of physics in not good enough to relate to your story ;-)

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