Re: PMDD's

> From: Paul Rothel <prothel at bright_net>
> Subject: PMDD's
> From what I have 
> learned from this list the iron content for plants to grow and be healthy 
> in aquariums is about .15 mg/l.  I already have tap water(well water) 
> with a iron content of .07 mg/l.  Am I right in thinking that this iron 
> is not chelated iron and is of no help to my plants.  If so then, should 
> I adjust the iron content in my aquatic water to read .07 plus .15, 
> making a total of .22 mg/l?

	The point about non-chelated iron is that it very soon
precipitates out as iron(III)oxohydroxides.  If the iron in your
well water precipitates out in your tank/filter, then it won't
appear in your water test result.  Make your measurements a few
days after a water change, and aim for the concentration you want -
don't make any adjustment.
> Also since I have never heard of a way to check for the Potassium Sulfate 
> content in my aquatic water,  how do I know how much to use in my PMDD 
> recipe?

	It is not easy to test for potassium in water, without using
fancy equipment.  Fortunately, neither potassium nor sulphate is likely
to build up to concentrations that cause problems as long as you do water 

	I have received e-mail from the U.K. which gave municipal water
analysis with potassium, sulphate and nitrate concentrations that
were so high (thanks to agricultural contamination of groundwater) that
the sender would never have to bother with anything but trace element
addition to his tank, provided he did water changes.  The fish seem
to survive.

Paul Sears    Ottawa, Canada