Keep a close eye on the A/N/N readings. Two weeks isn't really enough
time for a tank to properly cycle, and you will likely see at least a
small cycle. If you start to get Ammonia/Nitrite readings ... do water
changes.

Yes, I thought that ammonia testing at zero so soon was a bit curious. I
guess I've yet to see the spike. Will test every day for awhile.

OTOH

from what you have posted, this tank is well past cycled, no need to even worry about it.

We're aiming for a reef tank, so I'd like to see some coraline algae in
there, if only to give the Coral Beauty something to nibble on. He
hasn't been eating much (if any) of the flake or frozen I've been
feeding.

try nori, its dead so no worries about it spreading.

Will kalkwasser lower alkalinity and raise PH?

it will raise both, how far depends on how much you add, IMO start adding it now. assuming
the "kalkwasser generator" works

Can I just remove some tank water, say a gallon, add a bit of salt and
mix well, then return it to the tank? Via the sump, perhaps? A little
bit per day...?

yep thatll work fine. 1 gallon at 1.025 2x will start to make a dent.

After you wait out any potential cycle, and do a couple water changes to
bring your parameters in check, you might want to think about beefing up
your cleaner crew considerably - a bunch of different snails, maybe a
brittle or serpent star, etc.

i'd skip starfish unless its part of the "guidelines"

Should I put in some live sand first?

one or the other, if you add the LS slowly over time, you will not disturb much.




--
Richard Reynolds