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Re: a few questions

On Wed, 19 Apr 2000, Jason Luebke wrote:

> I have a few questions that I hope someone can answer:
> 1.) I use 100% re-constituted RO water. Since I use Roger Miller's recipe
> for re-constituting RO water, I assumed that 30% weekly water changes would
> provide all of the Mg and Ca the tank needed (I re-constitute for 3-4 dKH
> and 3-4 dGH). Is this a bad assumption? In short, the tank parameters are
> 125 gal., 420 Watts, heavily planted, 1/8 tsp KNO3 + 1/8 tsp K2SO4 daily +
> PMDD micronutrients daily (CSM), Ph=6.8, and CO2 injected.

The Ca and Mg supply should be adequate.  The recipe was intended to give
alkalinity and general hardness close to the values that Amano reports in
his first book.

> 2.) Is there some other nutrient not in PMDD or Roger Miller's recipe for
> reconstituting RO water that I am missing since I don't use any tap water?

The recipe supplies only the major ions that are typically found in water,
and it should supply those in a balanced fashion.  It doesn't supply
nitrogen, phosphorus or any of the minor or trace nutrients.  Fish feeding
alone may be adequate to supply those nutrients.  If you want to add
chemicals to be positive then make sure that your PMDD provides *all* of
the essential nutrients except Ca and Mg.

> 4.) Does someone know of a good source for phosphate that I might be able to
> find without any trouble? I know someone had suggested Hach, but I was
> hoping that it was more easily available at a hardware store or something.
> Someone also mentioned muriate of potash. I am not sure what that is and
> cannot find it anywhere. Can someone enlighten me?

Muriate of potash is potassium chloride.  It contains no phosphorus except
as an impurity.  The most readily available phosphorus sources are jobes
sticks and phosphate-based buffers.  If you choose to use a phosphate
buffer keep in mind that you will need very little of it.  I ran through
this calculation a few weeks (months?) back.  It would be best to check to
original letter but my recollection is that - at least for the Seachem
product - you might want to use about 1/1000th of the recommended dose.

Roger Miller