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RE: dH/TDS

Since no one replied I will take a shot.

On 08-Sep-00 Ryan Deal wrote:
> Hello,
>     I was wondering if there is any "link" between dH and TDS. 
>

Not much.

dH or GH is total hardness. It is measure of combined carbonates, sufides,
sulfates, silicates, etc.

TDS is a measure of ion conductivity.

Now the ions that will contribute to GH will also contribute to TDS, but the
recipricol is not the case.  Things like NaCl or KCl will contribute greatly to
the TDS but very little if any to the GH.  So your question:

>For instance,
> if the water had a dH range of 7.0-9.0, what would that be equal to in TDS
> terms (if they are related at all?).
>

can not really have an accurate answer.  If the mono ion concentration is
constant then the TDS might be an indicator of GH but you would need to
calibrate it for your water. In fact, I really do not know why people use TDS
with Killies.  It is used a lot with Discus and this is becuase at the dH (0 -1)
that people use to raise Discus, if the TDS is low the slime coat on the Discus
is inhibited.  This makes successful fry rearing very hard.

I know of no corresponding situation with Killies.  I use the American
Pharmaceuticals GH and KH test kits and use no measure of TDS.

> I just ordered my R.O. unit and I was
> wondering how to measure the dH?
>

I use the American Pharmaceuticals GH and KH test kits and use no measure of
TDS.

> I am buying a pH and TDS meter and I am
> wondering if I can use the TDS meter to get an idea of what the dH is? Do I
> need to get another meter for the dH? I notice that in most books they give
> you the dH that the fish prefers, but nothing about the TDS.
>

Thus the logic of measuring GH and not TDS.

>     Also what is the best way to change the dH of my R.O. water? When I
> change the dH of the water am I adding buffers?
>
Aquarium Phamiceuticals and Kent both make a product to adjust dH from R.O.
water.  I think they are both called R/O Right.  Aqua Pham's is a liquid and is
much easier to use.

Note that you often have to do a small pH adjustment too.  Do this after you do
the R.O. adjustment.  Don't waste money on the pH adjustment chemicals.  a 10:1
ration of Baking Soda/Soda Ash (available at swinging pool supply stores). It
will be the same thing for about 1/100th the cost

>     If there is anyone out there that would like to give a dissertation on
> dH, TDS, pH, kH, etc. and how they work together and how they can be changed
> and measured to get the optimal parameters from the R.O. water, it would be
> GREATLY appreciated.
>     Thanks in advance for any replies.
> 
> Thanks,
> Ryan
> ryand at mtxaudio_com
> 
> 
> ---------------
> See http://www.aka.org/AKA/subkillietalk.html to unsubscribe

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Date: 11-Sep-00
Time: 12:01:18

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