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[APD] RE: nitrogen

> Ok. I assumed mistakenly that nitrogen would only be present in a water
> column in the form of NH3, NO2 and NO3.

NH3 and NH4 always exist together in an equilibrium determined by pH (at higher pH, you tend to have more NH3 and less NH4 and vice versa). For the purposes of fertilisation, I think the difference can be ignored. Both are (sort of) forms of ammonia.

> Does this mean that algae (green water one) prefers (consumes faster) 
> NH4 or it takes in only NH4 and alike, not NO3? The reason for my 
> question is that you want to maintain NO3 slightly above zero, so as not 
> to starve higher plants, isn't?

If you have a high level of ammonia, you will get green water. But then, ammonia is toxic, so you don't really want any...
Plants and algae both consume ammonia - in a heavily planted tank the action of the plants absorbing ammonia means that you can get away without a filter in many cases (though the bacteria are useful as a backup if plant growth stalls for some reason).
Also, you do NOT want to maintain NO3 slightly above zero. This is a myth. You can have high levels of NO3 without algae. You should have, as a rough guide, at least 5-10 mg/l of NO3 to support very healthy plant growth. Healthy plant grows stops algae (just don't ask me why!). I think the guidelines are that you should then have a PO4 level of 1/10th of you NO3 level, and a K level twice that of your NO3 level (in a 1:10:20 ratio of PO4:NO3:K).
> Pardon my ignorance, but where ( or from which product ) does KNO3 comes 
> from? For example potassium supplement by Seachem claim to contain 
> soluble K20.

Buy it as a chemical powder, or as a fertiliser powder.
As a side note, I don't believe that the potassium supplement by Seachem actually contains any K2O, but due to silly fertiliser laws, it is required to describe the amount of potassium it contains by the amount of K2O that would have the same amount of potassium (bizarre or what?). I also think it says that somewhere on the bottle, at least I think that's the case on the Flourish supplement.
> So, basically you are advocating implanting new tank with bacterial 
> culture from established aquarium. Still, I don't exactly understand 
> which bacteria eats NH4 and how does it fit in the nitrogen cycle. 
> Perhaps then, someone could point me to a more developed nitrogen cycle 
> diagram than simple
> NH3 -(bacteria)-> NO2 -(bacteria)-> NO3 -(consumed by plant)-> plant 
> -(fish eat plant)-> NH3

Fish food gets eaten by fish or decays, producing ammonia. Then either:
a) algae/plants use up the ammonia
b) bacteria turn it into NO2 and the NO3, which is then absorbed by plants
Then either:
a) Plants die/get eaten and ammonia is produced, hence the cycle, or
b) you remove plant material from the aquarium, thus removing nitrogen.
But we can add NO3 in the form of KNO3 or similar to feed the plants.

> Why? How will this [drop off of CO2] affect level of NH3/4 if I have very little fish in it?

Lack of CO2 hinders the plant growth, while algae doesn't care much. Hindering plant growth leads to algae...
> However, I've seen plenty of tanks which did not seem to have UV or 
> diatom filters and yet had crystal clear water.

Feed the plants properly, and you don't get algae in the first place. I think Tom was merely suggesting short term solutions that work to physically remove the algae as you correct nutrient levels.
> But wouldn't stimulating higher order plants help them to consume more 
> NH3/4 and thus make it a limiting factor in algae grows?
Yes. Fertilise them with KNO3 and KH2PO4 and traces.

> Ok. Do you know by chance what is exactly in Seachem Flourish Nitrogen?
> They do mention that it is derived from urea, but claim on the same page 
> that "no free ammonia is released because the ammonium in Flourish 
> Nitrogen? is complexed and unavailable until utilized by the plants.".

I think it is just that - a locked-up form of ammonia only the plants (and possibly the bacteria) can use.


Whatever you Wanadoo:

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