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Re: More GW notes

James asked:
> 
>> The higher plants would either have to
>> compete with the biofilter for ammonium

I over looked this question. As it is a valid one I try to respond to this.

The algae/bacteria relationship is one that they are quite similar(both
small very fast exponential growth/ high efficiency->more mass directly into
growth). The bacteria normally will have a greater advantage. Why? Lighting
is the biggest one. No intense light, no GW. Bacteria don't need the
light(except for BGA etc). This is one reason I hate chemical snake oils and
why they seldom work.

They are simpler (not simple themselves) than the plants.
Plants are much more massive than the algae or bacteria. They are effected
less by low NH4's than are the bacteria/algae(think growth rates
also->bacteria and algae have extremely fast generational times). They take
in much more NO3 in aquatic environments than NH4(unless we want dead fish
etc). They (plants) will grow better if we have higher NH4 but not a great
deal more. They will assimilate the NO3 and make NO2 them finally make NH4.
You get the same thing in the end anyway. It takes more energy to do this
but it's worth it.

 NH4+ is very toxic and plants cope with this by rapidly converting the the
NH4+ into amino acids. This is why low levels like those produced from a
moderate fish load waste cycle is good and important. If your concerned
about this NH4 getting to your plants it will behoove you to feed regularly
and well. This will give enough NH4 for the plants. Let the NO3 do the rest.
Plants can handle it and it's associated human error much better than adding
nutty things like ammonium sulfate. Your not going to get that much out it
by adding it.  
Bacteria and algae since they are faster at growth, they also respond faster
to this "easy food"... if you will. They can rapidly use it since they don't
have to "pull it into them" where it can build up to high levels.

Many studied have been done on the relative amounts of these NO3's and other
amounts of N contain compounds in plants. There is a wide range of % mass in
many different plants. All plants do not have the same amount/ratio. Compare
the clover/cocklebur with white lupines/radishes. Very large make up
differences. What these are in aquatic plants? I don't know:) Rice would be
a good one to look into.

 Plant will use the NH4 and have preference energetically for it but it's
not that plants would want only NH4. They prefer a BALANCE of ions of NH4+
and NO3-. This ratio may be explored in the future but its elusive in an
aquatic environment since the NH4+ gets used so fast.
But both plants and algae have abilities to super concentrate the
ions/chemicals that need for growth. Some of this is truly amazing.

Following the NH4 vs. the NO3 is rather difficult even if you label them.
But you could try to set up an experiment with only one(NH4+ or NO3-) to
figure out which goes where. From there perhaps you could guess a bit better
as to this balance and what is optimal for the plants. This has been studied
in ag crops a great deal but in soil ecology this is difficult also since
everything eats everything else. Food web hell. But Aquatic ecologist are
light years ahead of the soil ecologist in a many ways. But it's an
interesting field to say the least. Lots of questions and they are big
questions that related to ag crops, aquariums and us.

Back to swamp:)
Regards, 
Tom Barr