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Re: Getting the red out

> Tom, at the risk of opening this thread again (and you know it's been
> running on the Sfbaaps list for years), I thought we found that red
> coloration was stimulated by stressing, limiting **either** N or P in
> the presense of an adaquate supply of K and the other nutrient.

> In other words, running relatively high NO3 and strict limitation of P
> with the occasional PO4 "pulse" produced large, luscius red leaves in R.
> macrandra (I should note here that IME macrandra is sensitive to N and
> doesn't thrive in environments with more than about 10ppm or less than
> 3ppm).
> Reversing the proportions had a similar effect: relatively high PO4
> (above 2.0ppm!) and less than 1ppm of NO3 forced just about everything
> else in my aquarium that could turn red to do so.

This method gives the best color I've seen. But some plants respond
negatively to low NO3.

 ***Or*** is it that respond negatively to low NH4?
The NO3/NH4 dynamic cannot be ignored if we seek to understand and use this.
If the tank has a high enough snail, fish, shrimp etc population it will
increase the NH4 perhaps even to the point where little or certainly less
NO3 is needed.

 In fact, the
> macrandra went blood-red, but of course the leaf size was stunted from
> lack of NO3.

I got great color at higher NO3(10ppm) and high PO4(1ppm). Could be the
harder water. We got the same lights, CO2, K+, test kits, etc. I also got
this in Marin. I recall it did not like the (too)low NO3 in the no fish
shrimp tank but did better out front with the higher fish load. Kinda wonder
how much of the NH4 vs NO3 is responsible. Well, that's the next question
now that we have somewhat of a handle on color:)
> Michael Rubin in San Francisco, where it looks like a good day for a
> middle-aged run ~

And hopefully not a middle aged pace:) A beach run with a soccer ball sounds
like order of the day for myself.
Tom Barr