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[APD] Re: Aquatic-Plants Digest, Vol 22, Issue 16
I have a 50g, moderately planted & slightly overstocked.
Many times (because of work - that's my excuse anyway) my NO3 levels climb
well above a hundred for weeks at a time & the water also develops a quite
distinct yellowish tinge (for other reasons I believe).
I never get algae under these circumstances (I've been running the same
tank, with many of the same fish, since 1998).
I DO get algae when the O2 levels fall.
This is usually either because the pump (Eheim external) has become very
badly choked, or is broken (as happened with my previous Fluval) & the flow
rate has dropped significantly.
Over a period of a few weeks the algae starts to get quite bad.
When that happens I clean the pump (not always changing the water) &, again
over a period of a few weeks, the algae goes away.
It's very predictable.
Anyone else seen that?
----- Original Message -----
Date: Tue, 14 Jun 2005 10:08:06 -0700 (GMT-07:00)
From: Thomas Barr <tcbiii at earthlink_net>
Subject: [APD] NO3 limits in planted tanks
To: aquatic-plants at actwin_com
I found out that NO3 levels over 120ppm do NOT cause nor induce algae in
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
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
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
So I still do not know what PO4 or trace element level is toxic and causes
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
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
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