could you give me some more kalk slurry info?

to do the slurry the correct way you need to own (or at least borrow) a pH
monitor as a test kit will not be accurate enough.

first you have to find the daily demands of your system, this is done by
testing the Ca levels of the tank and then not adding anything to the tank
other then RO/DI top off water. after 3 days (the longer you wait the more
accurate the test) and retest Ca to see how much it dropped. divide that
drop by the # of days to get the daily demand.

now with the pH monitor on, you want to watch the pH as you add the slurry
to the tank. start with a small amount 1/4 tsp in a cup of RO/DI water
slurried around til it's mixed completely. then dump the slurry into a high
flow area of the tank (not the sump)

you don't go by the initial spike but the total rise in pH after the tank
gets a good mix (about an hour) at that time you don't want more then a 0.2
spike in pH. I've had as high as 1.9 initial spike and never had any
problems from corals or fish from it.

in my 180g (250g total system volume) to boost pH I can add a full
tablespoon in a quart of water and dump it in with no problems.

hth
kc