Calcium reactor and kalkwasser

[rmurken]

That's not a good plan. Saturated limewater has a pH around 12.54 (at 25 deg C), and 11.54 is less than 10% saturated. 10.54 is less than 1% saturated.

Who said there’s no drama to chemistry.

 

[Dennis Cartier]

As it would happen, I have started up an Avast Kalk stirrer to assist with lowered PH from a CaRx. This time I am using the Milwaukee EC meter that I had purchased specifically for monitoring the kalk strength (back when I used kalk before). The meter lists it's range as 0 to 10ms, but I was able to confirm it is able to display a bit over 10ms using some tank water and RODI.

I am looking forward to see if the addition of using EC will take the guess work out of kalk usage.

Dennis

 

[shar_zard]

@Dennis Cartier Any luck with the conductivity probe, I'm thinking of doing a similar setup

 

[Dennis Cartier]

Sure, I can give an update on the plan. I found that the EC probe was showing a slow decline in kalk strength using the Avast reactor. I am only pushing about 4L per day through, so I assumed the kalk was getting too much exposure to CO2, caused by the low flow, even though a layer of undisolved kalk remained on the bottom of the reactor.

I decided to switch to a Geo 8" kalk reactor where the solution has little contact with air. I only switched a few days ago. I have the reactor mixing for 1 minute every 12 hours. I started it up with about a cup of kalk, and the EC probe read 10.3 mS/cm and I am now seeing a slight decline on a daily basis. Today at noon it read 8.6 mS/cm and 9.3 mS/cm after the mixing cycle ran.

I plan to add 14 teaspoons of kalk on a weekly basis, so it will be interesting to see if the EC tracks back closer to 10.3 mS/cm after the first refresh (this weekend).

Also, I am dosing continuously through the reactor without any pause after mixing, but have a settlement stage that I constructed out of an RODI cannister to catch any kalk particles. Working great so far.

Dennis

 

[Randy Holmes-Farley Verified Community Expert]

Sure, I can give an update on the plan. I found that the EC probe was showing a slow decline in kalk strength using the Avast reactor. I am only pushing about 4L per day through, so I assumed the kalk was getting too much exposure to CO2, caused by the low flow, even though a layer of undisolved kalk remained on the bottom of the reactor.

I decided to switch to a Geo 8" kalk reactor where the solution has little contact with air. I only switched a few days ago. I have the reactor mixing for 1 minute every 12 hours. I started it up with about a cup of kalk, and the EC probe read 10.3 mS/cm and I am now seeing a slight decline on a daily basis. Today at noon it read 8.6 mS/cm and 9.3 mS/cm after the mixing cycle ran.

I plan to add 14 teaspoons of kalk on a weekly basis, so it will be interesting to see if the EC tracks back closer to 10.3 mS/cm after the first refresh (this weekend).

Also, I am dosing continuously through the reactor without any pause after mixing, but have a settlement stage that I constructed out of an RODI cannister to catch any kalk particles. Working great so far.

Dennis

It might be that the solid material just does not dissolve to reach saturation unless it is actively stirring. .

 

[Dennis Cartier]

It might be that the solid material just does not dissolve to reach saturation unless it is actively stirring. .

Hmm, when I added the new kalk this weekend, the meter read 10.2 mS/cm after mixing, which it had not reached in several days. It seems to have reverted to only reaching 9.6-9.7 now again.

As an experiment, I will extend the mixing to 10 minutes from 1 minute to see if a greater saturation is reached with a longer mixing cycle.

Even with the less than 100% saturation, I am much happier with the Geo reactor than the previous Avast. The Avast dropped in a gradual decline even though the stirrer was running 24x7.

Dennis

 

[Randy Holmes-Farley Verified Community Expert]

Hmm, when I added the new kalk this weekend, the meter read 10.2 mS/cm after mixing, which it had not reached in several days. It seems to have reverted to only reaching 9.6-9.7 now again.

As an experiment, I will extend the mixing to 10 minutes from 1 minute to see if a greater saturation is reached with a longer mixing cycle.

Even with the less than 100% saturation, I am much happier with the Geo reactor than the previous Avast. The Avast dropped in a gradual decline even though the stirrer was running 24x7.

Dennis

That's good to know.

Thanks for the info.

 

[Dennis Cartier]

After increasing the mixing time to 10 minutes, the EC reading still only reaches 9.3 by the end of the mixing period. Over the 12 hours of dosing, before the next mixing cycle, the EC meter drops to 8.3, then is driven back to 9.3 with the mixing.

So increasing the mixing time by x10 did not impact the saturation that was reached after a mixing cycle. Adding fresh kalk will drive the saturation back to 10.2, but I still have 3/4" of undissolved kalk on the bottom of the reactor, so I am going to monitor the highest point post mixing and see if I can use up a bit of the undissolved surplus before adding more fresh kalk.

Dennis

 

[Randy Holmes-Farley Verified Community Expert]

After increasing the mixing time to 10 minutes, the EC reading still only reaches 9.3 by the end of the mixing period. Over the 12 hours of dosing, before the next mixing cycle, the EC meter drops to 8.3, then is driven back to 9.3 with the mixing.

So increasing the mixing time by x10 did not impact the saturation that was reached after a mixing cycle. Adding fresh kalk will drive the saturation back to 10.2, but I still have 3/4" of undissolved kalk on the bottom of the reactor, so I am going to monitor the highest point post mixing and see if I can use up a bit of the undissolved surplus before adding more fresh kalk.

Dennis

This is one of the reasons I'm not a fan of limewater (kalkwasser) reactors.

Folks assume they are dosing saturated limewater and often are not.

nevertheless, these values are pretty high and you cannot expect to get a lot more out of it, even if it was saturated.

 

[Dennis Cartier]

This is one of the reasons I'm not a fan of limewater (kalkwasser) reactors.

Folks assume they are dosing saturated limewater and often are not.

nevertheless, these values are pretty high and you cannot expect to get a lot more out of it, even if it was saturated.

Yes, I am quite happy with the result as long as it is consistent. The kalk is mainly to offset the PH effects of my CalRx, so I am not reliant on it as the sole means of supplementation.

Interestingly, I lowered the dosing rate last night by about 12.5%, and the EC meter is only down to 8.5 as of now (mix cycle starts in 1 hour). It would normally have hit 8.3 by now. So the range of high to low, can be controlled by more frequent mixing to limit dilution.

Dennis