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[APD] Re: Gw/NH4

Sep 13 Thomas Barr wrote:
> > Steve P > Aquatic plants can store
> > reserves of nitrogen and will do so quite efficiently.
> Why add KNO3 then? Just once a week or a month?

Hi Thomas,

I've been re-reading the archives to try to figure out the origin of the
green water & vacation discussion and it seems to predate September. Serves
me right for joining in the middle. :-)

Actually I think there might be a good advantage to adding nitrogen in
relatively larger doses infrequently if you're battling with removable
algae. Since the algae can grow faster than vascular plants, initially
you're going to get a good burst of algae growth but the plants are also
going to absorb & store enough to double or triple in mass. After a week or
so you can harvest the algae, or another fast growing plant like Salvinia.
Perhaps you change out much of the water to reduce the water conditions to
low N. Then you can let the plants grow out for several weeks relatively
free of algae competition. You can kill green water in a couple of days of
darkness too. With furry algae like Oedogonium, perhaps you need to chop off
the worst affected leaves, or just leave them if you can get the water to
the point where the fur algae can't grow back onto new leaves. This is sort
of the approach I'm using with my Lace plant coexisting with three Bettas.
Unfortunately, the Bettas need enough high-protein/tasty food that there
seems to be little likelihood of seriously forestalling the return of the
filament algae. I've recently harvested several large clumps of filament
algae. The lace plant has new, clean leaves. The Crypts & other plants have
become a forest but so far, everything is still going. I also need to toss
in another spoonful of CaCO3 & a healthy glug of potassium & magnesium
concentrate every couple of months or so.

I'm not really sure how long it would take for a plant to bring all of its
tissues up to full sufficiency of nitrogen. From what Paul wrote, it sounds
like only a few days.

Steve P

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