So my RO/DI water is very weird. The TDS comes out at 2-3 ppm (due to terrible water), but also comes out with high carbonate hardness, which is 8-9 DkH. Right now my water is 3 ppm and 8 DkH. This test has been done by many test kits, including the LFS testing it. However, according to @Randy Holmes-Farley, this is probably not possible. Can someone explain this?
Low TDS, high alk.
- Thread starter Earl Karl
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You earlier said 0 ppm, which is impossible.
As a rough test, 3 ppm tds is roughly 3 mg/l of some salt. Assuming it is nothing but sodium bicarbonate (which itself is impossible, but assume it is) then 3 mg/l is 0.04 mM = 0.04 meq/ L = 0.1 dKH.
So it is still not possible and must be alk test error or tds measurement error.
As a rough test, 3 ppm tds is roughly 3 mg/l of some salt. Assuming it is nothing but sodium bicarbonate (which itself is impossible, but assume it is) then 3 mg/l is 0.04 mM = 0.04 meq/ L = 0.1 dKH.
So it is still not possible and must be alk test error or tds measurement error.
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Has to be testing error. Alkalinity is a dissolved solid and will read on a TDS meter.
I don't know enough about the way Alk test kits work to know if it is possible for a small amount of contaminant to show up as high alkalinity. Regardless, one or the other isn't accurate.
Just checked with my LFS. Alk test says 8 DkH but tds is 260... whoops. Guess I need a new tds meter lol. My tap comes in at 500. So, my ro/di system is terrible, well it is old so it served its purpose. Time to get a new one I guess. Dam.
I don't know if I can trust any digital meter anymore.
I don't know if I can trust any digital meter anymore.
Yes, it sounds like there's an issue with it. Does it read 0 ppm TDS in air?
You might get a standard and check it for accuracy. This sort of thing:
https://www.hach.com/calibration-st...tandards/family?productCategoryId=35547408081
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