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Re: [APD] NO3 limits in planted tanks

Are you claiming that nigh NO3 and PO4 levels under all
conditions do not induce algae growth? Or are the
circumstances limited in which they do not?


--- Thomas  Barr <tcbiii at earthlink_net> wrote:

> Well, 
> I found out that NO3 levels over 120ppm do NOT cause nor
> induce algae in any way.
> That said, it does cause certain plant species to melt
> (but not Crypts as often erronously stated in past
> literature and repeated anecdotal comments across the
> web). 
> I found the LD 50 for NO3 and Amano shrimp.
> (LD 50-> the level at which 50% of the organism is killed
> occurs over a given exposure time, often used in
> toxicology protocols) 
> 3 day exposure at 100+ppm will cause them to act sluggish
> and slowly die off. 
> Fish were unaffected but showed some signs of stress.
> Some plants showed signs of slower growth or leaf melt. 
> NO3 was from purely KNO3 inorganic inputs. 
> This again is interesting because at 100ppm of NO3 I did
> see some negative plant response(inhibition/toxicity) but
> no algae responses. 
> It seems that negative plant responses are more of an
> issue with the upper ranges of the macro nutrients rather
> than any issue of inducing algae.
> I have still yet to have found any PO4 that causes plant
> inhibition.
> Still, given these extremely high nutrient levels, I
> think it's very safe to say that excess nutrients over an
> extremely wide range causes no algae blooms.
> Perhaps the rest of the folks on the list can explain
> this to other folks that still suggest algae or plants
> outcompete eachother for these resources(impossible
> obviously when the levels are 5ppm PO4/100ppm NO3---all
> in bioavailable inorganic forms), or that excess
> nutrients induces algae(other than NH4/unstable CO2) that
> these issues are simply not true.This will help stop
> myths that have long been established and further the
> hobby. 
> I tested high levels of Trace elements a few months ago
> and found that using SeaChem's Flourish at 100
> milliliters/per 100 liters of tank (or 10mls per liter of
> tankl!!) did not cause any shrimp toxicity nor any
> negative plant response over a 7 day time frame. The
> water was very dark during this time from all the trace
> elements. 
> Again, this clearly shows that excess, or high levels of
> Fe and other trace elements such copper have no adverse
> effects or impacts on flora or fauna.
> So I still do not know what PO4 or trace element level is
> toxic and causes plant inhibition.
> But..........it's extremely unlikely someone wilkl make
> their water tea colored with trace elemtns or add more
> than 10 ppm of PO4.
> Therefore the usable range of all needed plant nutrients
> is enormous without any negative flora or fauna impacts.
> The issue is really one of nutrient levels that are too
> low, rather than too high. 
> There are limits, but they are so high that it's only in
> the context of a purposeful extreme over dosing that this
> occurs, far beyond normal hobby error.
> Regards, 
> Tom Barr
> www.BarrReport.com
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> Aquatic-Plants at actwin_com
> http://www.actwin.com/mailman/listinfo/aquatic-plants

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