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Re: Aquatic Plants Digest V4 #632

Cavan wrote, Oct. 26:
>I remember but can't find something someone mentioned
>something about how Rotala macrandra is redder with
>potassium sulfate than with kno3.  In my tank, I
>always add the sulfate form, but the plants are not as
>red when I add kno3 as well.  Why exactly is this?
>That said, and knowing that aquatic plants prefer
>ammonium to nitrates, would we get better growth and
>color adding VERY weak additions of ammonium or
>ammonia daily?  I cringe as I write this, but I think
>it may have some merits.

My guess is that your macandra is redder with the potassium sulfate than
with the potassium nitrate because it was somewhat nitrogen deficient.
Plants getting enough nitrogen are greener and grow faster.  Thus, it is
not surprisng that they may develop less red color.

Don't go too far with this notion that plants perfer ammonia to nitrate.
They may take up ammonia faster than nitrate when given both, but they do
very well with nitrate, only, and can take it up even from very low

I have a suspicion that all the Rotalas grow best when nitrogen levels are
low, and some time I would like to test this idea.  They seem sensitive to
heavy additons of nutrients, reacting by growing tiny, distorted leaves.

Paul Krombholz, in central Mississippi, where the drought continues.