RE: TDS & pH Meters

[listhub@libros.andante.mn.org]

No one answered so I will venture a answer.

First off, I would look for a article in the upcoming Journal of the American
Killifish Association by Wright Huntly entitled something like "Water
Chemistry for Dummies" or some such.

There really is no "relationship between hardness and TDS".  TDS is a measure
of devolved solids in the water.  It is similar, but not the same as
conductivity and is based on a conductivity measurement.  If anyone reading
knows the difference please chime in.

That having been said we take up the subject of hardness.  Old school aquarium
books talk about GH and KH.  GH is a measure of divalent cations (mainly MG++
and CA++) and KH is a measure of Carbonate concentration.  Now both these
things contribute to "hardness" and can effect the TDS reading.  Where things
get confusing is that the reverse is NOT true.  Something can have a high
TDS and a low GH and KH, for example a solution of NaCl or FeCl.  So it is best
to talk about TDS for a given hardness.

IMHO, TDS meters have one use.  They tell me if the water the fish is in and
the water I want to put him in have the same osmotic state.  It is really the
osmotic state that effects transfer of the fish and this is pretty well
indicated by TDS.  In fact, again IMHO, I think that given similar TDS, changes
in pH do not really effect fish unless super drastic such as 6.5 > 8.0.

So I use a TDS meter when I want to move fish.  When I want to know what the GH
or KH is, I measure it using one of the liquid drop test kits.

All comments welcome.  Fish keepers love to talk about water!

john
On 11-Oct-00 Max Gallade wrote:
> I received my pair from Hanna yesterday also and started immediately
> fiddling with them.
> My tapwater reads tds  158ppm at a pH of 7.4 .I lower my ph down to 6.6~6.2
> with CO2 Injection and peat filtration in my 75g.
> The  holding tank for waterchanges reads a tds at 150 ppm- peat filtration
> also.
> My growout and breeding tanks measured between 150~170ppm.
> Are these readings TDS considered good (soft) for apistos?Chemistry and
> physics classes are so long ago.I understand that there is no direct
> relationship between hardness and tds.What tds do you all shoot for ,around
> a 100ppm?
> Z-man do you have to keep the pH meter in a holding solution like Hanna's
> manual suggests? Any recommendations?BTW,know I understand how you dropped
> them in a tank :),almost happened to me last night.
> TIA
> Max
> 
> -----Original Message-----
>> From: owner-apisto@admin.listbox.com
>> [mailto:owner-apisto@admin.listbox.com]On Behalf Of WnyZman@aol.com
>> Sent: Tuesday, October 10, 2000 3:02 PM
>> To: apisto@majordomo.pobox.com
>> Subject: TDS & pH Meters
>>
>>
>> Just wanted to say that Hanna was great as I have already revceived my 2
>> meters ordered in just 7 days. BTW, I called them on the 800# instead of
>> through the Internet. Both are just like the one's I purchased
>> over 10 years
>> ago but eventually dropped them in the tanks. Those worked great
>> and I assume
>> these will also.
>>     Z-Man
>>
>>
>> -------------------------------------------------------------------------
>> This is the apistogramma mailing list, apisto@listbox.com.
>> For instructions on how to subscribe or unsubscribe or get help,
>> email apisto-request@listbox.com.
>> Search http://altavista.digital.com for "Apistogramma Mailing
>> List Archives"!
>>
> 
> 
> 
> -------------------------------------------------------------------------
> This is the apistogramma mailing list, apisto@listbox.com.
> For instructions on how to subscribe or unsubscribe or get help,
> email apisto-request@listbox.com.
> Search http://altavista.digital.com for "Apistogramma Mailing List Archives"!

----------------------------------
E-Mail: listhub@libros.andante.mn.org
Date: 13-Oct-00
Time: 16:21:27

This message was sent by XFMail
----------------------------------


-------------------------------------------------------------------------
This is the apistogramma mailing list, apisto@listbox.com.
For instructions on how to subscribe or unsubscribe or get help,
email apisto-request@listbox.com.
Search http://altavista.digital.com for "Apistogramma Mailing List Archives"!