Richard Sexton wrote:
In article ,
Robert Flory wrote:

"Elaine T" wrote in message news:vlmId.13778
The red colors on your plants are from the light intensity. That's one

of the really fun results of high light intensity and good amounts of
iron. Spot algae is one that likes high light intensity, which is why
you're seeing it now. I'd actually try dropping the nitrate rather than
increasing because you have a lot of fish in the tank, but don't drop the
K.


Actually the reds may be a sign of nitrate deficiency, or so I recall seeing


Absolutely. Add nitrates and plants become more green. But red plants are always red,
this isn't going to turn them all green, just a bit less red.

Conversly you can redden up your plants for a picture by restricting nitrate.


Interesting. There's a sound biological reason for what I said.
http://www.sciencenews.org/articles/20021026/bob8.asp explains it.
Bright light causing anthocyanin production in plants has been well
documented. Basically anthocyanins are reddish pigments that help
protect a plant's photosynthetic mechanism from being burned out by too
much light.

Reddish aquarium plants like Hygrophila polysperma "sunset", Rotala
indica, Rotala macrantha, Ludwigia spp., and many Crypts and swords do
not display their reddish colors under inadequate light. It takes a lot
of light for anthocyanin production to come into full swing, thus my
reaction that the red was due to high lighting.

Does anyone know the physiological explanation for reddening due to
nitrate deficiency?

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__ Elaine T __
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