At What pH is Kalk No Longer Fully Saturated

[Reefahholic]

In a closed container it does not decline (IME). In an open container it can, especially if the crust that forms on the surface is broken up (IME). The article below shows a number of experiments. Here are two of them:

The Degradation of Limewater in Air - Reefkeeping.com

Figure 2. The conductivity of the limewater in my dosing reservoir as a function of time.

Figure 6. Conductivity as a function of time for initially saturated limewater that has no excess lime solids present. The liquid was kept in an open container and the surface crust that forms was broken by the conductivity probe where indicated. The data in red is reproduced from Figure 5 (where there is excess lime and no breakage of the crust). Note that the conductivity scale is blown up considerably (compared to all other figures) to see the drop.

Great graphs! That makes sense. I’m gonna leave it alone and slow dose it 24/7. Really appreciate the info!

 

[Reefahholic]

Randy, go to 9:00 on this video. Chris M. Was taking about that very thing.

 

[Lionfish hunter]

I'd be wary of trusting calibration at the usual 7 and 10 for reading above 12. Hence the method Jim and I refer to.

The solids that remain may be impurities such as magnesium hydroxide or calcium carbonate, or those insoluble things may crust over solid particles of calcium hydroxide, preventing dissolution..

I don’t have the means to calibrate my ph probe above 10. Using 7 and 10 to calibrate should still give okay results for comparing know saturated kalk against kalk I am dosing right? I just checked saturated kalk 12.6 to my kalk reservoir 12.59. Even if the 12.6 isn’t exactly correct, being .01 off between the 2 should mean it is almost at saturation correct?

 

[Randy Holmes-Farley Verified Community Expert]

I don’t have the means to calibrate my ph probe above 10. Using 7 and 10 to calibrate should still give okay results for comparing know saturated kalk against kalk I am dosing right? I just checked saturated kalk 12.6 to my kalk reservoir 12.59. Even if the 12.6 isn’t exactly correct, being .01 off between the 2 should mean it is almost at saturation correct?

In post 2 of this thread, that is how I advised testing it: compare to saturated kalkwasser. Assuming that solution is actually saturated and at the same temp, then a drop of 0.01 pH units means a drop in potency to about 98% from 100% saturated.

 

[Lionfish hunter]

In post 2 of this thread, that is how I advised testing it: compare to saturated kalkwasser. Assuming that solution is actually saturated and at the same temp, then a drop of 0.01 pH units means a drop in potency to about 98% from 100% saturated.

Okay thanks