Kalkwassser pH lower than expected

[gdtpgh]

After recalibrating my Pinpoint pH probe and getting good readings at 4.0, 7.0 and 10.0 on a whim I decided to check the pH of my kalkwasser. I expected it to be close to 12.0 but the reading I got was around 10.5.

It was not a fresh mix of kalkwasser. I had added water to the 5 gal barrel and mixed it up about an hour or two before I tested it. It had not completely settled and was a bit milky. There was still plenty of kalk mix in the bottom of the container.

Any thoughts?

 

[bertoni]

[welcome]

How much lime per gallon was added to the mix? How long was it mixed? An hour is a very short time for the pH to drop much.

I wouldn't particularly trust a pH meter to register accurately given those calibration points, but that is rather far off. If it's measuring the tank properly, though, I wouldn't worry too much.

 

[gdtpgh]

I'm not too worried about it but having just calibrated the probe, I expected is closer to 12. I typically add kalk to the barrrel every week to 10 days. Maybe it's just time to dump the residue and make up a fresh batch. I also seem to recall reading somewhere that not having a clear solution may affect the probes ability to get a good reading. It's a brand new probe and it's accurate using the calibration liquids so I have to assume my tank reading is ok too. Just thought I'd push the envelope and see if I got to the 12.0 reading on the kalk.

 

[bertoni]

A pH probe calibrated at 10.0 and not higher can be expected to have some problems, but that reading is very low. I'd try mixing at least a bit of fresh solution to saturation (at least 2 tsp per gallon). A cupful would be fine.

 

[davidryder]

What the the ratio of kalk to water? Do you know for sure?

 

[gdtpgh]

I mix my fresh kalk at 2 heaping teaspoons per gallon. I don't discard the mix for several weeks and keep adding kalk around 1 heaping teaspoon per gallon as I dose it into the tank. There is typically a lot that is settled out at the bottom of the container so I never felt I needed to add much more....given the reading, maybe I do.