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Re: Aquatic Plants Digest V3 #200

Jim Wilson wrote:

> These are the characteristics of my tap water according to my city
> (Portland, OR):
> 	pH - 7.1
> 	NO3 - 0.02 ppm
> 	NO2 - 0.002 ppm
> 	Phosphorus (PO4) - ND (not detectable) @ 0.003 ppm
> 	Phosphorus, Total (P) - 0.005 ppm
> 	Hardness (as CaCO3) - 5.1 ppm
> 	Alkalinity (as CaCO3) - 6.2 ppm
> 	Carbonate (as CaCO3) - ND @ 0.1 ppm
> 	Bicarbonate (as CaCO3) - 6.2 ppm
> 	Calcium (Ca) - 1.2 ppm
> 	Magnesium (Mg) - 0.50 ppm
> 	Potassium (K) - 0.30 ppm
> 	Sodium (Na) - 2.7 ppm
> 	Copper (Cu) - 0.070 ppm
> 	Aluminum (Al) - 0.087 ppm
> 	Iron (Fe) - 0.031 ppm
> 	Manganese (Mn) - 0.002 ppm
> So how does it look?  Seem to be OK.

Looks to me like its very nearly rain water.  There's nothing wrong with
the water and I wouldn't suggest doing anything to it without some
experience that indicates you need to.  There are some things you might
look out for.  The alkalinity is low and this might make for an unstable
pH.  Increasing alkalinity (with CaCO3, for instance) would help stabilize
that. Also calcium, magnesium and potassium are all low and if you want to
support elevated growth rates then you may need to use a supplement that
provides more of those.

> Should I be concerned that any great changes would occur as the water
> traveled from the source (place of testing) and my kitchen tap?

Different systems will vary on how they report their water quality.  These
may be "at the tap" values and may very well be an average from several
different taps over a period of time, but in many cities the quality will
vary from place to place.  Check with you water utility to find out where
the samples are taken and what period of time they represent.

In my town (for example) there's a lot of variation from place to place
because water in different areas comes from different well fields.  The
city reports values from (as I recall) 27 different taps spread out around
the system so there are three or four sampling point in each service area.
They report averages and maximums over annual periods.

Roger Miller