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Re: Nutrient deficiency

On Sun, 11 Jun 2000, Josh Liechty wrote:
> In my 20 gallon 'long' planted aquarium I have observed a strange growth
> pattern of Hygrophilia difformis. The original plant (which I have had
> for over 7 months) grew smaller, filled in leaves, instead of the bushy,
> fern like leaves of the cuttings which had been removed from it and are
> growing on the other side of the aquarium.

That sounds like the normal emersed form of the leaves.  H. difformis are
commercially grown emersed and it's fairly common to see the emersed form
of leaves on newly purchased plants.  I couldn't say why the original
plant didn't revert to a submersed growth style, but it probably isn't a
nutrient problem.

> The new leaves of the old plant were (were: I removed the old plants
> yesterday) also yellowish.
> According to the charts on the nutrient deficiency page at the krib,
> this might be a deficiency of nitrogen, calcium, iron, or sulfur. Please
> help if you have any idea.

General yellowish color is probably caused by a shortage of nitrogen. You
have very few fish in this tank so it looks to me like your plants' yellow
color is probably caused by nitrogen deficiency.  You can also check the
condition of older leaves.  It's common (not necessarily universal) with
nitrogen deficiency for older leaves to die back from the tips. An iron
deficiency creates interveinal chlorosis (green veins, light colored areas
between veins) appearing first on young leaves and sulfur deficiency is
pretty much unheard of.  A calcium deficiency would cause deformed growth,
but you don't seem to have deformed growth.
> Question #2: From what little reading I have done about the marine side
> of the hobby, I know that some of them think that it is bad to use
> mechanical filtration constantly in their marine tanks, because it
> removes the beneficial plankton. Are there any opinions on mechanical
> filtration in the freshwater planted aquarium?

Mechanical filtration is optional.  I keep a filter around for occasional
use.  A mechanical filter that's left on a tank permanently tends to
become a biological filter.

Roger Miller