- Apr 22, 2020
- Reaction score
If I knew in high school that chemistry would be important later in my life for the health of my animals I would have paid more attention during the lessons.let's explore that in detail.
Suppose that you have fresh water with an alkalinity of 1.0 dKH (0.36 meq/L).
It must have either
0.36 mM hydroxide (OH-)
0.36 mM bicarbonate (HCO3-)
0.18 mM carbonate (CO3--; carbonate carries two units of alkalinity)
There must also be counterions present since one can never have just negative charges in water.
Let's assume it is sodium, which is most likely, but the assumption doesn't matter much. In each case, we will have a total of 0.36 mM sodium to balance charge.
How conductive are each of these solutions? We can look them up.
0.36 mM (14.4 mg/L or 14.4 ppm) sodium hydroxide has a conductivity of about 31 ppm TDS
0.36 mM (~30 mg/L or 30 ppm) sodium bicarbonate has a conductivity of about 20 ppm TDS
0.18 mM (19.1 mg/L or 19.1 ppm) sodium carbonate has a conductivity of about 20 ppm TDS
Thus, if the RO/DI water has a TDS of 0-1 ppm, it really cannot have anything close to 1 dKH of alkalinity. Maybe 0.05 dKH max for 1 ppm TDS.