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Re: Nutrient deficiency
>From: "Roger S. Miller" <rgrmill at rt66_com>
>There is a detail about nutrient deficiency symptoms that I don't remember
>reading on this list. A symptom of nutrient deficiency is caused by a
>shortage of the nutrient *in the plant*.
Right on!
That might not mean that there's
>a shortage of the nutrient *in the aquarium*. The plant may be unable to
>get the nutrient or it might lose it too quickly to keep enough in the
>plant.
Excellent point...(Roger, I thoroughly enjoy reading your posts)..... I
have observed similar behaviour in a diverse plant community tank and I
suspect it is because some plants are hogging the critical nutrient(s).
>For instance, Echinodorus of all types fail miserably in one of my tanks
>with symptoms of both calcium and potassium deficiency.
A few other
>species in the same tank also develop potassium deficiency symptoms. This
>is despite dosing the tank with enough Tetra Florapride to push the
>potassium content up over 10 mg/l, adding enough potassium chloride to put
>in another 10 mg/l and adding calcium carbonate directly to the substrate
>around the affected plants.
--- other details omitted----
>The tank where the Echinodorus fail had a coarse substrate of sealed
>aquarium gravel and Tex-Blast. The tank where the symptoms disappeared
>has a more fine-grained substrate of Tex-Blast and fine river sand.
Both
>substrates are very well aged and have a population of trumpet snails. I
>don't really understand why the grain size of the substrate would make a
>difference, but I speculate that the roots don't function very well in a
>coarse substrate and that's enough to trigger the shortage.
I recently had a similar problem in a 125g tank with a diverse population
of plants. Several of the plants were doing great, but a few types were
crasing. One example was my Hemianthus micranthemoides all of whose older
leaves got have holes. This plant used to grow like a weed. What happened
is that I ran out of my regular fertilizer and decided to temporarily make
my own brew. I am pretty sure I was giving them the right amounts, but was
dosing weekly instead of daily. After fiddling with the formula for over a
month... adding extra Mg and K to boost the concentrations a few ppm, I
finally did some testing -- I concluded that the water did not have enough
iron...either the chelator in the trace element mix was not keeping it
available long enough or my other plants including a large Echinodorus
hormanii were soaking it up and keeping it away from the more delicate
plants. The parallel to Roger's expereince may be unavailability of iron in
aerobic conditions. It is possible that his plants were not getting as
much iron in the coarse substrate compared to the more annoxic fine
sand/clay. The thing that makes these problems trick is that not all
plants in the same tank will show the symptoms of a deficiency.
Neil Frank