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Re: Potassium and notes on hair algae

On Thu, 2 Sep 1999, Ed Street wrote:

Regarding potassium...

> weeks)  BTW all the net searches I have done so far have resulted in a
> lack of information on potassium in planted tanks/rivers/ponds/etc..
> Seems the biggest thing i've found is potassium nitrate info.

There is a truely staggering volume of information on the net regarding
potassium, nitrate and other nutrients in streams, rivers and other bodies
of water.

You might start with the data reported for the National Water-Quality
Assessment Program (NAWQA).  They offer several downloadable data sets.
One you might find particularly interesting is the stream and river
nutrient data at:


you will need to download three files:  the explanation, the site
descriptions and the data table.  The data table includes 8,459 chemical
analyses, from streams and rivers all over the country including clean
rivers, polluted streams, fresh streams and estuaries.  I think the
Chatahoochi river is included.

If that isn't enough, then find the website for your local district of the
US Geological Survey.  Some districts are setup for online queries of
some very large public water quality data bases.  You may (for instance)
be able to find water quality reports for your favorite aquatic
plant setting from every month over the last 50 years or so.

Except for a few local instances I doubt that you will find any
relationship between potassium and nitrate.


Regarding hair algae...

> Perhaps phosphates are high (one of the reasons why iron is very very low
> since phosphates bonds with iron)  but then again am not really positive
> of the effects of phosphates on algaes.  I have been reading about redox
> potential and algae growth lately tho.  (again phosphates are another,
> like potassium, that's lacking in information on)

I wouldn't be surprised if phosphorus is high, but < 50 ppb isn't low
(much less very, very low) for iron.  Less than 5 ppb is probably low.  I
wouldn't sweat redox potentials too much if I were you.

> My original point was I now do not believe that iron has an effect on hair
> algae, at least this strain that is, and quite possible nitrogen? however
> if this is the case then there IS something that dictates it's growth and
> it would be very helpfull to find that nutrient.

The algae is dependent on some form of dissolved nitrogen.  No green algae
is capable of fixing nitrogen, but I read just last night that some algaes
might be able to utilize nitrogen in dissolved organics.  I have no idea
how widespread that behavior is.

There are something like 21 different essential nutrients for plants and
algae.  All of them have to be available and any one of them potentially
controls the growth of algae, but most of them are needed in such
miniscule quantities that shortages are unlikely.  The ones that are more
likely to cause problems are the elements needed in large quantities (i.e.
carbon, nitrogen, potassium, calcium) and those that are needed in minor
amounts but sometimes difficult to obtain (i.e. phosphorus, iron).

Of course, in our synthetic environments any of the essential elements
could become limiting but we rarely need to look beyond the elements that
are needed in the largest quantities.  Karen Randall writes an excellent
column for AFM.  Early in her series (but available in AFM's archive) she
blessed us with a two part article on plant nutrition.  Algae nutrition is
pretty much the same.  The article is a good read.

Roger Miller