Kalkwasser Ph?

[WVReefJunkie]

I have had to up my dose of Limewater because my Alk is falling, and I have a question about Ph of saturated Limewater. I dont currently have a conductivity meter to check Limewater, but was wondering why when I mix two teaspoons of Kalk in a cup of RODI water I get a PH of 11.5, shouldnt the Ph read 12.4? Does this tell us the Kalk powder has lost potency? Thanks

 

[Randy Holmes-Farley Verified Community Expert]

I have had to up my dose of Limewater because my Alk is falling, and I have a question about Ph of saturated Limewater. I dont currently have a conductivity meter to check Limewater, but was wondering why when I mix two teaspoons of Kalk in a cup of RODI water I get a PH of 11.5, shouldnt the Ph read 12.4? Does this tell us the Kalk powder has lost potency? Thanks

It is more likely the pH meter is not properly calibrated for reading at that pH.

Make a standard with 2 tablespoons of calcium hydroxide slurried in a CUP of RO/DI water, mix a bit, and measure the pH. Then use that same meter to measure the pH of the solution you want to know the potency of. A drop of 0.1 ph unit is a drop in potency of 26%, 0.2 ph units is a drop 37%, and a 0.3 pH unit drop is a decline of 50% (all because pH is logarithmic).

 

[WVReefJunkie]

It is more likely the pH meter is not properly calibrated for reading at that pH.

Make a standard with 2 tablespoons of calcium hydroxide slurried in a CUP of RO/DI water, mix a bit, and measure the pH. Then use that same meter to measure the pH of the solution you want to know the potency of. A drop of 0.1 ph unit is a drop in potency of 26%, 0.2 ph units is a drop 37%, and a 0.3 pH unit drop is a decline of 50% (all because pH is logarithmic).

I figured out why my reactor wasnt keeping up with Alk demand anymore, one of the Dos tubing lines that feed the reactor was getting blocked. I did take the ph probe out and inserted the probe in my tanks water. I was getting 8.22 with the displays probe, and 8.49 with the Kalk reactors probe.