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Re: Potassium Sulfate and Potassium gluconate
Beverly Wladyka is wondering about sources of Potassium...
> We have an on-going algae problem in our planted 180 gallon Amazon
aquarium. Experimenting
> over the past several days, I've been trying to find the optimal daily
macro- and
> micro-nutrient dosage and have been using the recipe from
> http://WWW.CAM.ORG/~tomlins/algae.html as my guide. However, this recipe
calls for potassium
> sulfate and above potassium gluconate is suggested as the potassium
source.
Bev, if you'll re-read the original post and my response, you will notice
that the person was suspecting a Potassium deficiency. The reason I
suggested dosing with Potassium gluconate was due to the fact that using it
you are adding ONLY Potassium (ignoring for the second the gluconate, which
is not used by plants). Dosing with a specific nutrient is one of the only
SURE ways for the amateur without access to a full blown laboratory to
conclusively diagnose a particular nutrient as being in short supply. Using
Potassium sulfate (or sulphite - same thing, different spelling - American
english vs. British english) would add Phosphorous and Sulfate (Sulfur),
both of which are essential elements. While it is highly unlikely that
sulfate would be in short supply in most waters, (sulfate is _usually_ the
second most prevelant anion in freshwater, after carbonate), it _could_ be
and so you couldn't test for a Potassium deficiency by using it, as it could
solve either a Potassium deficiency OR a Sulfur deficiency.
> According to our city's water treatment website at
> http://www.aqualta.com/pages/about9a.html, our tapwater has a sulphate
range of 58.5 - 97.0.
> Is the sulfate in the potassium sulfate compound and the sulphate listed
at the city water
> treatment website the same? If so, it would then make sense for us not to
use more sulfate (in
> the form of potassium sulfate) in our 180 but to use potassium gluconate
instead, correct?
I doubt that the extra sulfate from the fertilizer would cause problems
combined with your water. Sulfate is a macronutrient and plants need a lot
of it. As was pointed out by Paul K. regarding target levels for Potassium,
there can be quite a range which is acceptable - I suspect that a similar
case could be made for supfate.
> By the way, what is the chemical symbol for potassium gluconate?
Check the archives - I believe that either Roger Miller or Greg Morin gave
the chemical formula for gluconate several months ago during a discussion of
Seachem's Flourish Iron.
> Are there sources of potassium other than sulfate and gluconate for
aquatic use? I ask because
> going the drugstore route to use potassium gluconate tablets for a 180 is
going to cost big
> bucks over the long term.
If you find Potassium sulfate to be cheaper than the pills from the
drugsore, I see no reason why you can't use it for refular fertilization of
a tank.
James Purchase
Toronto