PH probe for kalkwasser

[Geoology]

I have a PH probe in my kalk stirrer. I added to help me know when to add kalk. The PH probe is constant 12.2 but after a couple of weeks I see the tank PH start to drop by a small amount add kalk to stirrer and then within a day the PH in the tank is back to 8.2-8.3. Is there something I am not doing right to in the stirrer?

 

[Lasse]

Most pH meters have a upper range. I would guess that your pH meter only shows up to around 12 and therefore your real pH in the calk stirrer is above 12.2. Max pH any solution can have is 14 - at least in my schoolbooks

Sincerely Lasse

 

[Reckless]

I stopped using my kalkstirrer for that same reason. The probe in my stirrer was at 12.3-12.2 but the ph in my tank would keep dropping. Even after adding more kalk than recommended it would still drop in the tank but not the stirrer. Then I made 5 gallons of kalk water and my probe read 12.4 and doesn't changed for 2 weeks. My tank ph is now 8.2-8.3 and I don't think I'm going back to the talk stirrer. my guess is the stir bar add CO2 to the kalk keeping it from being fully saturated.

 

[Adamantium]

I was recently told that pH of kalkwasser isn't indicative of saturation, at all, and that was my experience. A VERY light solution of kalkwasser was reading 12.3. I think it just reads high no matter how much you put in (to a certain lower limit).

I believe the better indicator is electrical conductivity, and/or TDS.