So basically you need to add as much as needed tp match your alkalinity consumption or total evaporation whichever happens first.
If the total evaporation is too much for Alkalinity addition you prepare a less potent more diluted solution, and as mentioned above if total evaporation is not enough to maintain your alkalinity then you need to add additional supplement.
You have a couple of different methods to estimate how much:
a) Trial and error test drip test drip and such.
b) Measure your evaporation by measuring how much water you add on a daily basis (or weekly divided by seven
)
Measure your alkalinity consumption: Measure the alkalinity then wait exaclty 48 hours without adding any supplement and measure again.
Use the chemistry calculator to detemine the amount required of Lime water to change the alkalinity equivalent to your consumption.
That is the amount of saturated lime water you need to add over two days to match your consumption. If this amount is larger than your evaporation then add the evaporation and get ready to add other supplement. If it is less than your evaporation, prepare a diluted mix and add your evaporation.
c) If you are adding a supplement that you wish to replace then use the chemistry calculator to determine how much alkalinity you are adding and use the data to determine how much lime water will be needed.