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Re: Nitrogen Deficiency

Steve asked about his Hygrophila corymbosa and nitrogen

It wouldn't surprise me if it is a deficiency of N, Steve, since H.
corymbosa is such a fast grower.  It does however sound like you
have an adequate fish population in this aquarium, as well as a fairly
rich substrate.  Is the Hygro growing emersed?  I have several very
large shoots of this plant, and its cousin H. salicifolia, growing
emersed in a gravel/laterite substrate, in a 10-gallon aquarium with a
very small fish population, which I recently described in a posting
about tiny tanks.  The only water additives I use at water changes
are some dechlorinator, some Duplagan, and some store-bought
aquatic plant fertilizer (Kent's).  It seems I inadvertantly created the
ideal conditions for experimenting with nutrient deficiencies <g>.
The Hygro is such a fast grower I can almost hear the nutrients
being sucked up into the plants :)  Recently, two things happened.
The first was that the older leaves began to turn yellow and ugly
brown patches began to form near the leaf edge and spread inward
until the leaf ultimately died and dropped off.  The second thing was
an outbreak of cyanophyta.  I tested for nitrates with my LaMotte kit,
and sure enough, nitrates were pretty well depleted.  Anyway, I at
least had the foresight to order some KNO3 a few months back and
it was sitting in the basement waiting for an occasion to be called
into service.  I mixed up a solution of 1 teaspoon per 500 mLs of
water and started dosing the tank with a medicine dropper, albeit
somewhat haphazardly.  Both the leaf-yellowing situation and the
blue green invasion now appear to have abated.  My next task will
be to mix up some PMDD and try it out.  I would not advocate
throwing nitrates into your tank unless you are sure you need them,
but in this case the addition of the KNO3 really seems to have

Jonathan in Maryland
Energetics, Inc
7164 Gateway Drive
Columbia, MD 21046
(410) 290-0370

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