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Re: Plant growth/condition as indicator

>Date: Sat, 20 Sep 1997 12:43:48 -0400
>From: Jeff & Denise Dietsch <dietsch at voicenet_com>
>Subject: Re: Plant growth/condition as indicator
>Hello all,
>   Ron has mentioned using Hygro and sword species as indicators of a
>nutrient balance/excess/limit in the aquarium.  I know others have
>mentioned at least the red color in ludwigia and other red plants as an
>indicator of iron content.  Another indicator is the loss of lower leaves
>of stem plants as an telling you your light is to low or a general lack of
>plant foods.  I am very interested in this as I currently adjust my PMDD
>mix based more on the look of the plants then the test measurements.  But
>having say a list of these kind of conditions would be great.  I have tried
>searching the archives, but outside of reading most all the posts I have
>not really been able to formulate a list.  If we get some response, I can
>formalize a list and publish it on my page and forward it to the list for
>the archives.  So Please if you have a an observation like this send it
>here or to me personally and I will tabulate it.
After a almost a year, I've settled on the following recipe for "PMDD":
2 tablespoons KNO3
1 teaspoon    KSO4
1 tablespoon Microplex - micronutrient mix
1 tablespoon of MgSO4-7H2O
270 ml H20
There's reasons why I deviated from the "standard" mix. I believe the process 
of adjusting the mix was interesting, so hopefully I'll share it with a posting
real soon.
>>Sunset Hygrophilia polysperma ... is excellent in monitoring iron levels.
>What does it do, loose the pink color??
I'm in the process of writing a article to TAG magazine that further details
the use of this plant as monitor of nutrients, so here I'll just give a quick
I grow the Sunset Hygrophilia polysperma in a pot that only has rock wool
in it.  I DON'T dig the roots into the gravel, so that all the plants
nutrients only come from the water column.  Even under these conditions,
the plant still grows 1 to 4 inches a day in my aquarium.
When the light levels and iron levels are sufficient, the plants leaves
become a bright vibrant pinkish color.  When there's not enough iron, the
leaves only have a dull pink-yellowish color.
If I had a descent iron test kit, I could quantify this a little better.
I shoot for a iron reading of 0.1 ppm which happens to be the first 
division for comparing the levels in my test kit.
>  With the water softener, did you ever try using potassium chloride
>instead of sodium chloride.  The salt substitute is available for water
>softeners for people on low salt diets, and the price is similar.  Plus the
>added potassium and lack of NaCl is only a benefit to the tank and your
>family.  Although I am not sure that the concentrations really make much of
>a difference, I know the loose of the NaCl would be a good thing:)
Jeff, I like your idea on using potassium chloride in the watersoftner.  The
softener will replace the CaCO3 and MgC03 with K2CO3.  The water will
now have potassium for the plants and CO3 ions for maintaining the KH & pH
stability.  When I started growing the aquatic plants, I had troubles
with excessive Nitrate levels.  When measured with the Tetra Nitrate
test kit, I found the tap water to have about 25 ppm Nitrate Ion and
my about 50 ppm in the aquarium.  Thanks to people on this list, I now know
( i.e.        [NO3-] = 4.4 [N-NO3-] )
that 25 ppm Nitrate ion is about 5.5 ppm Nitrate Nitrogen, which would
be about the right amount of nutrients I would need to add to my now
more or less Nitrate/Phosphate limited tank.
I did buy a RO unit for water changes, perhaps I could of saved a little money.
Ron Wozniak  Allentown PA, USA
rjwozniak at lucent_com