about TDS

What is TDS ? and how i can get the calculation of it manually without
devices.
Thanks , William

I don't know of any way to measure this without a meter.

It's not like they are expensive. you can get a tds meter for $15 or less.
--

Margolis
http://web.archive.org/web/200302152...qs/AGQ2FAQ.htm
http://www.unrealtower.org/faq

William Creznavetch wrote:
What is TDS ? and how i can get the calculation of it manually without
devices.
Thanks , William


If you boil away a litre of aquarium water until you are left with a
white salty residue, this is the Total Dissolved Solids. But you would
still have to weigh this residue with a "device" to get the TDS. A gram
of this substance would mean a TDS of 1000 ppm. I use a TDS meter which
measures the resistance of the water to infer the value. Much easier!

Nikki

In article , says...
I don't know of any way to measure this without a meter.

It's not like they are expensive. you can get a tds meter for $15 or less.


Must agree, a meter is the way to go.

TDS = Total dissolved solids

For the sake of discussion, one could get close by evaporating all the water and
weighing what remains. This would capture all the dissolved minerals, the dominant
component of TDS in an aquarium.

The laboratory procedure would be to take a clean 1 litre flask and weigh it. Then
add 1L sample water, and boil it down until the flask is dry. Then weigh the flask
again and subtract the empty weight. The difference is the weight of the minerals
in 1L water. The number of milligrams is roughly equal to the TDS in ppm. The
scale has to be pretty good if the water is fairly pure since you will be
subtracting two large numbers to get a small result.

William Creznavetch wrote:
What is TDS ? and how i can get the calculation of it manually
without
devices.

TDS is a (roundabout and ambiguous) measure of the electrical
conductivity of a water, which in turn is a measure of the salinity of
the water. TDS means "Total Dissolved Solids", but that's misleading,
as it's not what it measures; a TDS-meter measures electrical
conductivity and recalculates this from microSiemens per centimeter to
milligram per liter (milligrams of what? well, it differs).

This means that TDS can not be measured except with an electronic
conductiometer. Evaporating a sample as has been suggested in this
thread will give too high values due to uncharged molecules (e.g.
sugars & lipids) and due to suspended solids such as dust, plankton,
bacteria...

As is probably obvious I would suggest measuring just conductivity, and
avoiding the IMO pointless recalculation of conductivity into ppm
whichever salt or salt-mix the manufacturer of the meter has decided
to use for conversion.

For a good treatment of TDS see he
http://www.reefkeeping.com/issues/20...ture/index.htm

(I would especially recommend those who feel like pressing the reply
button to tell me I'm wrong to read the above link *first*. It'll save
time.)

wrote in message
oups.com...
William Creznavetch wrote:
What is TDS ? and how i can get the calculation of it manually
without
devices.

TDS is a (roundabout and ambiguous) measure of the electrical
conductivity of a water, which in turn is a measure of the salinity of
the water.

I think your intro is reversed, it should read:
"Measuring the electrical conductivity of water is a roundabout method of
determining the level of TDS."

I think you and the article explained everything very well after that.
--
www.NetMax.tk

snip
For a good treatment of TDS see he
http://www.reefkeeping.com/issues/20...ture/index.htm

(I would especially recommend those who feel like pressing the reply
button to tell me I'm wrong to read the above link *first*. It'll save
time.)

Thusly "NetMax" Spake Unto All:

TDS is a (roundabout and ambiguous) measure of the electrical
conductivity of a water, which in turn is a measure of the salinity of
the water.

I think your intro is reversed, it should read:
"Measuring the electrical conductivity of water is a roundabout method of
determining the level of TDS."

I don't really see that. I mean, yeah, it's good to know the
conductivity of the water, and yeah, the conductivity is dependent on
the amount of dissolved salts.
I just question the use of measuring conductivity but expressing it as
fictional milligrams of the wrong salt per liter. I really don't see
the point.

IMO, measuring the conductivity is useful only to judge the purity of the
water. While it does indirectly indicate TDS and/or salinity to some
degree, there are better ways to measure those. A conductivity meter on the
output of a RO/DI system is a great way to see if the output is pure, and it
needs no calibration or cleaning.


"Mean_Chlorine" wrote in message
...
Thusly "NetMax" Spake Unto All:

TDS is a (roundabout and ambiguous) measure of the electrical
conductivity of a water, which in turn is a measure of the salinity of
the water.

I think your intro is reversed, it should read:
"Measuring the electrical conductivity of water is a roundabout method of
determining the level of TDS."

I don't really see that. I mean, yeah, it's good to know the
conductivity of the water, and yeah, the conductivity is dependent on
the amount of dissolved salts.
I just question the use of measuring conductivity but expressing it as
fictional milligrams of the wrong salt per liter. I really don't see
the point.

"Mean_Chlorine" wrote in message
...
Thusly "NetMax" Spake Unto All:

TDS is a (roundabout and ambiguous) measure of the electrical
conductivity of a water, which in turn is a measure of the salinity
of
the water.

I think your intro is reversed, it should read:
"Measuring the electrical conductivity of water is a roundabout method
of
determining the level of TDS."

I don't really see that. I mean, yeah, it's good to know the
conductivity of the water, and yeah, the conductivity is dependent on
the amount of dissolved salts.
I just question the use of measuring conductivity but expressing it as
fictional milligrams of the wrong salt per liter. I really don't see
the point.


I'm not questioning the wisdom of using conductivity to estimate the
level of TDS. I also agree that the accuracy will depend on the
percentage of conductive materials which make up your TDS. It's just
that the measurement method (conductivity) is not the measurement (TDS).

TDS is a parameter, which can be measured in different ways.

Conductivity is a characteristic. It's typically used to determine a
material's resistance (by taking the inverse of the mhos to give you ohms
of resistance). This is useful to determine if the material is more
insulator or conductor, and its suitability for various applications
(typically electrical, as it's the movement of electrons which are
influenced by a material's resistance or conductance). As a measurement
method, it just so happens to give a pretty good approximation of the TDS
level.

So conductivity (how you measure) is an indicator of the TDS level (what
you are measuring), not the reverse (at least not in any applicable sense
;~).

Oversimplified: temperature is not a method of measuring a thermometer -
a thermometer is a method to measure temperature.

I'm sorry if I'm not making myself clear enough, perhaps I'm nitpicking
anyways.
--
www.NetMax.tk

Thusly "Glenn" Spake Unto All:

IMO, measuring the conductivity is useful only to judge the purity of the
water. While it does indirectly indicate TDS and/or salinity to some
degree, there are better ways to measure those.

Actually, no, there aren't. There are other ways of measuring
salinity, ie relative density or refractive index, but not more
accurate, which is why salinity is defined as the electrical
conductivity ratio of a standard potassium chloride solution
(http://www.corrosion-doctors.org/Sea...definition.htm)

For TDS there's no other way period.

A conductivity meter on the
output of a RO/DI system is a great way to see if the output is pure, and it
needs no calibration or cleaning.

The reading you get on a RO/DI is usually the electrical resistivity,
not the electrical conductivity. They're pretty much the same thing,
but resistivity is the inverse of conductivity, ie as one grows the
other decreases.

I guess one could put it as that conductivity is a measure of _how
much_ salt there is in the water, whereas resistivity is a measure of
_how little_ salt there is in the water.

(If you're ever unsure, look at the units. Electrical resistance is
measured in Ohm, electrical conductance in Siemens. Resistivity and
conductivity are derived from these, and have Ohm*meter and
Siemens/meter as base units.)