This is my post from another current thread thread on the same subject:
There several ways to dose :
Neilsen tye reactors are sealed from the air ,so undissoved kalk can be kept in them and frequent stirring will not draw in CO2 from the agitated surface at the air water interface. Drawing in CO2 leads to precipitation and loss of kalk strength Some use them successfully ;some complain about the constancy of the saturation level and/or dosing cloudy water. They take little space and are nice if you like the technology stuff.
ATO dosing can work if the kalkwater is not agitated immediately before dosing. Overdosing, cloudy water and a a lack of constancy in saturation are reported with some frequency.
I prefer a still reservoir with a peristaltic pump, a diaphram pump is ok too. I use it for top off by setting the amount of water to be dosed each day. The timer breaks the dose into 150 increments over 24 hours. The amount is adjusted seasonally to match evaporation. If it's off a bit low ,a little ro/di water is added directly to the sump to make up any shortfall.The water is stirred once when kalk is added once a week or so and left to settle for 2 hours before starting the pump which draws clear kalk water through a tube placed in the reservoir( in my case a 32 gallon brute garbage can) about 2 inches up from the bottom to avoiddrwing in the slurry settlled at the bottom.. The can is covered but not sealed. The still kalkwater will hold it's strength for weeks unstirred in an unsealed covered container.
Some use a still reservoir with a gravity drip adjusted to insure agaisnst dosing too much at one time. Generally , 5 or more hours of dosing time for top off is minimal to avoid spiking ph and causing precipitation.
Some dose by pouring it in . Again attention to avoid dosing too much at once is required.