RE: [compost_tea] Re: Water Quality

From: John Cowan <vivax_at_northlink.com>
Date: Sat, 10 Apr 2004 10:36:13 -0700

Ted,

TDS does stand for total dissolved solids which means ionic minerals (i.e.
salts) not suspended solids. Materials like sugar will dissolve but are not
ionic. TDS is measured with a conductivity meter which measures the
electrical current that a water sample can carry. This is typically measured
in microSiemens, microMhos or ERGS which are interchangeable. 1000
microSiemens equals 1 milliSiemen. A meter shows TDS by multiplying the
conductivity times a constant. Usually I think this is 0.7 although it can
vary. Hence TDS is not a very good standard of measurement. To find the
actual amount of minerals in solution you need a laboratory chemical
analysis. Conductivity readings are good to know the ionic potential of a
liquid. This relates fairly well to the osmotic effect on living tissue.
Hope this helps.

John Cowan

-----Original Message-----
From: Ted Peterson [mailto:ted.peterson_at_tcsn.net]
Sent: Friday, April 09, 2004 10:07 PM
To: compost_tea_at_yahoogroups.com
Subject: Re: [compost_tea] Re: Water Quality


----- Original Message -----
From: Bill Pleasants
To: compost_tea_at_yahoogroups.com
Sent: Friday, April 09, 2004 7:29 PM
Subject: [compost_tea] Re: Water Quality


George Hahn advised me that water with total disolved solids more than 50
ppm

I must have misread one of my books. I thought TDS was Total Dissolved
Salts not solids. I guess I will have to reread some basic texts and see
where I got this wrong. However, can you tell me what difference Total
Dissolved Solids make with the tea? Since we are dumping compost into the
water and even if you use a bag (ugh!) some of the finer particles will fall
through the mesh and collate in the liquid if fine enough. My systems do
not use bags or chambers and so have a lot of suspended solids in the tea.

It just goes to show how little I really know. I totally mistook TDS for
salts not solids. Wow, does this change things.

Ted Peterson
Earth-Wise/Spirit of the Earth


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Received on Sun Apr 11 2004 - 23:15:03 EDT

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