[APD] Re: light

[Thomas Barr <tcbiii at earthlink_net>]

>Once a tank gets established, it can be rather amazing how
>much nutrients plants can suck up. And if one does frequent
>large water changes, the risks of excesses are lessened.

Which begs the question: what are excesses?

What is excess PO4?
What is excess NO3? 
What is excess K+?
What is excess trace?
What is excess GH?

Give a range in mg/L or ppm that causes issues for plants? 

I can only think of excesses in terms of fish for NO3 perhaps without going to really high extremes, but not the plants. they seem to enjoy 75ppm of NO3 just fine.

While we often say the risk of excesses, what the heck are those risk really?
Fish health for higher NO3, but it that purly jjst NO3 or is it from NH4 waste that reduce the O2 level, depressing the evironment? Or is it really NO3 inorganic forms? I've not seen any issues at 20-30ppm.
Some fish may breed with less NO3, but then again, they may breed at lower KH and better feeding and other changes. Correlation of one single parameter does not imply causation.


Regards, 
Tom Barr



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