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Re: Hardness in ppm /Red Rotala

>From: "Roger S. Miller" <rgrmill at rt66_com>
>I think this is always done on an equal equivalents basis.  In words, when
>magnesium is expressed as its calcium equivalent the number is the weight
>of calcium that would carry the same electrical charge as the weight of
>magnesium that's actually present.  It amuses me that someone, sometime
>thought this system actually made things easier!

Roger, thanks for answering my question. After hearing all the interesting
discussion about hardness, I decided to change my opinion about units: ppm
is really the preferred way to present hardness. 

Also important is to start presenting Ca++ and Mg++ concentrations instead
of Hardness.

Some manufacturers are starting to move in that direction. Maybe. <g>. 
Wardleys has a nice hardness test kit (they sent it to me as a
freebee)which reports total hardness and calcium hardness. Mg++ hardness is
calculated by difference. All are reported in ppm, which is nice. The only
concern is that they say that to convert ppm to DH you multiply by 0.056.
So it appears that they present the Ca hardness concentrations as ppm of
CaCO3 and Mg as the equivalent of MgCO3. So we are getting hardness as they
say, but not Ca and Mg concentrations. If this is true, does anyone know if
taking 40% of Wardley's ppm result will be an OK way get the approximate
concentrations of the Ca and Mg cations.

>From: Roxanne Bittman <RBITTMAN at hq_dfg.ca.gov>
>Continued discussion on red plants:
>One thing is for sure, the red you see in land plants is probably not
related to the red
>seen in true aquatics in the aquarium.  The red in the Rotala's we keep seems
>almost certainly related to light intensity, in my experience.  Perhaps it
is also
>somewhat related to light quality, but I doubt this.

Roxanne, why do you say that there is no relationship between aquatics and
terrestrial plants. I am not questioning your wisdom, just curious. I hope
it is not because of the Rotala model. I keep my Rotala very red at 1 watt
per gallon, using a combination of growlux and tritons-- and peat
substrate. The peat is 6-yrs old, so I do not think it is a big factor. The
rotala is not as red in another tank  with more intense light and different
spectra (with small amount of soil in substrate.).

>The red you see in the maple is a mystery to me; I'm sure somebody in
>knows why it gets red in the shade. 

Perhaps not relevant to this discussion, but shade light has a different
quality, especially after passing thru green leaves... richer in long wave
lenghts - reds and expecially far reds.
Neil F

>From: George Slusarczuk <yurko at warwick_net>
>In my opinion it is NOT the *conversion factors* that introduce the
>confusion, but the different "degrees" i.e. German, American, British,
>etc. You might assume that in a book published in England they will use
>English degrees (Clark) to measure water hardness, but I would not bet a
>nickel on it!

Thanks for letting me see the light. Opps wrong discussion <g>. I am now
firmly on the ppm bandwagon. George S's point is the main reason I now vote
to discourge use of "degrees" hardness as the preferred method. I reviewed
my older aquarium texts and the numerical conversion factors are different
in each book! 

Neil F.