Kalkwasser not dissolving.

[TWYOUNG]

I've always struggled with kalkwasser leaving more residue than I expected when mixed in vats even when covered as best as possible. Due to this I switched to a kalk stirrer and even run my carbon dosing, (vinegar), through the stirrer to hopefully increase the ability of the kalk to dissolve. Still I have always undissolved kalk building up in the bottom of the stirrer.
I add 25 to 50 gms powder weekly and use 3-4L of kalk solution daily. Is this normal? Should I add powder when there is accumulation in the stirrer or wait, although I don't know if it will ever dissolve. Currently I've decided to hold on adding more powder until I can see the tips of the stirrers fins. Thanks for your advice.

 

[Dan_P]

I've always struggled with kalkwasser leaving more residue than I expected when mixed in vats even when covered as best as possible. Due to this I switched to a kalk stirrer and even run my carbon dosing, (vinegar), through the stirrer to hopefully increase the ability of the kalk to dissolve. Still I have always undissolved kalk building up in the bottom of the stirrer.
I add 25 to 50 gms powder weekly and use 3-4L of kalk solution daily. Is this normal? Should I add powder when there is accumulation in the stirrer or wait, although I don't know if it will ever dissolve. Currently I've decided to hold on adding more powder until I can see the tips of the stirrers fins. Thanks for your advice.

How much kalkwasser are you trying to dissolve? Less than 2 g dissolves in 1 L of water. Also, it could contain a significant amount of CaCO3 which would account for some of the insoluble material you see.

 

[TWYOUNG]

How much kalkwasser are you trying to dissolve? Less than 2 g dissolves in 1 L of water. Also, it could contain a significant amount of CaCO3 which would account for some of the insoluble material you see.

As I said I use 25 to 50 gms powder per week and run 21 to 28 liters through the stirrer weekly.

 

[FishTruck]

Like Dan P says.... there should be undissolved Kalk (Calcium Hydroxide) in the bottom of the stirrer and a saturated solution of Kalkwasswer the top. Also, is CaCO3 (Calcium Carbonate) which accumulates as the Kalk reacts with air. As I understand it, the stirrer prevents a skin of CaCO3 from getting between the Kalk and the saturated solution but without allowing undissolved Kalk from getting into your tank.

I siphon or dump the contents of the reactor every two weeks as the amount of CaCO3 builds up and the Kalkwasser can lose potency. The part that truly won't dissolve is the CaCO3.

 

[Randy Holmes-Farley Verified Community Expert]

What brand kalk are you using?

 

[TWYOUNG]

What brand kalk are you using?

BRS

 

[TWYOUNG]

BRS

 

[Randy Holmes-Farley Verified Community Expert]

You should be able to dissolve 2 level teaspoons per gallon.

That said, reactors often product less than saturated limewater (kalk).

Undissolved calcium carbonate may be present in the initial material from CO2 entering it, and it can also form in the reactor or reservoir.

 

[TWYOUNG]

You should be able to dissolve 2 level teaspoons per gallon.

That said, reactors often product less than saturated limewater (kalk).

Undissolved calcium carbonate may be present in the initial material from CO2 entering it, and it can also form in the reactor or reservoir.

I'm curious as to why a reactor would produce less saturated solution than a bucket with kalk. I thought that was basically the reason for a reactor. It's a closed system which doesn't allow room air in except when I open it to add fresh powder. It also slowly stirs the undissolved material encouraging dissolution without so much agitation as to allow undissolved material into the tank.

 

[Randy Holmes-Farley Verified Community Expert]

I'm curious as to why a reactor would produce less saturated solution than a bucket with kalk. I thought that was basically the reason for a reactor. It's a closed system which doesn't allow room air in except when I open it to add fresh powder. It also slowly stirs the undissolved material encouraging dissolution without so much agitation as to allow undissolved material into the tank.

It takes time for chemicals to dissolve, with more flow giving faster dissolution. In a reactor where one is trying to keep particles in the lower part of the reactor to avoid dosing them, it is just an observed result that the clear fluid at the top often does not get saturated before leaving the reactor.

You can measure potency of the effluent a number of ways. Conductivity is easiest. PH works but is crude. Alk measurement is ok but needs dilution.

 

[TWYOUNG]

It takes time for chemicals to dissolve, with more flow giving faster dissolution. In a reactor where one is trying to keep particles in the lower part of the reactor to avoid dosing them, it is just an observed result that the clear fluid at the top often does not get saturated before leaving the reactor.

You can measure potency of the effluent a number of ways. Conductivity is easiest. PH works but is crude. Alk measurement is ok but needs dilution.

Measuring pH doesn’t work at all for me since I carbon dose vinegar through the kalk stirrer. Would the vinegar also effect the conductivity readings?

 

[Randy Holmes-Farley Verified Community Expert]

Measuring pH doesn’t work at all for me since I carbon dose vinegar through the kalk stirrer. Would the vinegar also affect the conductivity readings?

That’s kind of an unusual setup, and not something I generally recommend, although I expect it can work.

Is there a particular problem you are trying to solve by measuring?

Vinegar plus kalk will dissolve more kalk and have a higher conductivity.