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8 people found this helpful
A useful water quality meter - with a bit of work!!
on 24 June 2013
The EZ TDS digital meter is a simple to use and compact meter for `total dissolved solids' (hence TDS) and will measure essentially anything that affects the electrical conductivity of the water. A point to note is that any materials that do not affect this will NOT be measured!!
The unit is small and portable, measuring only 145x35x20 mm (approx) and runs via 2 x LR44 batteries contained in the lid (these are a bit fiddly to remove and replace) and also comes with a protective carry case. The measuring head needs to be immersed in the water sample, to the specified level, for about 45 to 60 seconds to allow it to stabilise the reading, then click the hold button. I asked a friend to check it against an industrial calibrated unit and we were surprised to find that the accuracy was very good, +/- 0.3% versus the industrial unit. There are only three operating buttons, the ON/OFF, the HOLD button to lock the reading and a TEMPERATURE reading button.
Because it measures total dissolved solids, this can make it a bit difficult to interpret the results when checking a domestic water filter, as it is also measuring the presence of material that a domestic filter cannot and will not remove. Therefore, you need to build up a few measurements and reference points to guide you in how well your domestic filter is working. Also try getting hold of some distilled water as a reference point.
I found that my water filter, (when new), will remove ~ 10 to 12.5% of total recorded solids on the minimum setting and 20 to 25% on the maximum setting. This allows me to monitor performance over time. It also shows how the water quality varies over time from the unfiltered tap as well, which can be more variable than you would think. I have had readings of 210 ppm up to 340 ppm TDS.
This makes things a bit more complicated if all you are interested in is `hard water salts', but still means that you can monitor the performance of a domestic filter. The alternative is to buy a set of hardness testing strips, but these are not quite as accurate or precise, I have found.
So, it is a decent, low cost meter, but with limitations if you are just interested in reducing water hardness, as you have to spend a bit of time in working out what the meter is telling you. I have found it to be a reasonable guide (with a little work).