When is Kalk used up?

[gfox]

I use a Kalk stirrer and the directions say to change out the kalk every 2 weeks.What happens after the 2 weeks does the kalk stop working?

 

[Randy Holmes-Farley]

If there is sufficient calcium hydroxide solids left, it can work fine, but some of what is there in the bottle is insoluble calcium carbonate and magnesium hydroxide, and those things accumulate over time (and calcium carbonate can be made in the reactor by CO2 entering from the air or with the water).

You cna monitor the conductivity of the effluent as the best way to monitor it (saturation is about 10.3 mS/cm at 25 deg C), but pH can be a cruder method and an alk test can work if the effluent is completely clear (no suspended solids).

 

[gfox]

If there is sufficient calcium hydroxide solids left, it can work fine, but some of what is there in the bottle is insoluble calcium carbonate and magnesium hydroxide, and those things accumulate over time (and calcium carbonate can be made in the reactor by CO2 entering from the air or with the water).

You cna monitor the conductivity of the effluent as the best way to monitor it (saturation is about 10.3 mS/cm at 25 deg C), but pH can be a cruder method and an alk test can work if the effluent is completely clear (no suspended solids).

I use the Kalk Stirrer also for my ATO.So when the Kalk is new what would the ALK read and what would it read after 2 weeks.Thanks for the info.

 

[Randy Holmes-Farley]

I use the Kalk Stirrer also for my ATO.So when the Kalk is new what would the ALK read and what would it read after 2 weeks.Thanks for the info.

I cannot tell you weeks because that depends on many factors, like how fast you are using it up. I do not know if your reactor saturates the limewater even when first filled since that is determined by how it stirs (and many folks mistakenly think it is saturated).

That said, saturated limewater at 25 degrees C has an alkalinity of about 40.8 meq/L or 114 dKH and 808 ppm of calcium.