The Stirrer is fed from my top-up tank via a small pump actuated by my float-valve.

I have quite a high evaporation rate due to my eco-cooler so the output from my top-up tank is split. This is tee'd off as in the pic so half the RO water goes through the stirrer & the other half goes directly into the sump. This is done to prevent over-dosing of Kalk due to the high evaporation rate.

The stirrer runs 24/7.

I add about 12 scoops of Kalkwasser powder into the Stirrer every 2 weeks or when the level gets below 2cm's.