Originally Posted by ScotJudd
Hi. I have and use a TDS
meter in my freshwater tank.
By monitoring the TDS
and the nitrates (separate test required) I can decide on the need for a water change. The rise in TDS
usually coincides with the rise in nitrates but is not a substitute for testing nitrates which has a much greater bearing on when and how much water I change. But it's easier to check TDS
daily with the meter rather than do a nitrate test daily (over kill I think).
Would I recommend a TDS
meter as an ESSENTIAL for a freshwater tank - no, but it is a convenient tool in your testing arsenal.
I'm pretty new to this so apologies but I have to disagree with the premise here.
meter measures electrical conductivity (period) and uses that to infer total dissolved solids (which really means ions in the water). Those can come from almost anything. There is no specificity in a TDS
meter at all. Conduction - period. While it may read in PPM
, that's relevant only for specific ions (usually salt), so it may read 300 ppm
and really be 150 of chemical A, or 400 of chemical B (or a mixture of the whole alphabet). You learn nothing about what is in it from the TDS
The OP seems to be saying they want a TDS
meter for ascertaining something about the health of the tank. I think that's a mistake. A TDS
meter will give you an indication of the purity of incoming water with respect (and only with respect) to solids that dissolve so as to conduct electricity. That could be anything from salt to calcium carbonate to dozes of other things. So a TDS
meter is great if you are buying (say) distilled water and want a quick check if the vendor is lying. Or buying RODI
water from a LFS
and want to see how well they take care of their filters.
And a TDS
is really good if you have your own water filter (especially RODI
, or even just RO
But as to testing the tank itself, my suggestion is you should look for test kits that test specific problem or target areas, e.g. nitrates, GH
, and forget the TDS
meter. It's just going to mislead you. Even the most directly connected two items (KH
) to a TDS
meter are best tested separately, as they target very different things, yet the TDS
meter lumps them together (in a pretty non-quantitative way).