Will this measure my water?

Hi HBT,
I have wanted to have my water tested for a while but my water comes from a variety of sources depending on various factors. Has anybody used something like this
I just wonder how well it works. It would be nice to know everytime what the composition of your water is.
http://www.austinhomebrew.com/product_info.php?products_id=12538&osCsid=61099928491888bdfdd3ab05b9d208db

Link is broken

Fixed it!!

That's a conductivity meter that is calibrated to read "total dissolved solids". It is calibrated against sodium chloride i.e. if you make up a liter of water with 100 mg of NaCl that device will read 100 mg. If you made a solution of 100 mg/L calcium chloride it would read something other than 100 mg but pretty close to it. It cannot distinguish between one ion and another so all it is really good for is checking on the output of an RO unit, for example. If it reads TDS 8 mg/L then you really don't care how much of that is magnesium, how much sodium, how much sulfate etc. because the level of all of those will have to be pretty low to give a total conductivity equivalent to 8 mg/L NaCl.

If you want more detailed information there are many test kits made for most of the parameters of interest (i.e. calcium, magnesium, alkalinity and chloride) with sodium and sulfate being the notable exceptions (there are kits for sulfate too but they are not so common and are not that sensitive). There are also kits for copper, iron, nitrate, nitrite and several other ions as well. Sodium is measured by an expensive, very slow responding electrode very like a pH electrode. Go to www.hach.com to check out the various kits. Also Cole-Parmer sells water test kits.

Kai has an article on using cheap and readily available aquarium testing kits to estimate residual alkalinity. With the caveats that this method will tell you nothing about individual ions and that it the accuracy is somewhere between ideal and a guess (likely closer to ideal if you carry out the test thoughtfully), here it is.

http://braukaiser.com/wiki/index.php/At_home_water_testing