Hey Rick, realy sorry to here this. Its a real heartbreaking task clearing a bunch of dead corals etc out of a tank. done it myself over the years on one of my own and a few friends so your not alone.
Re the kalk and top up. A system ive installed a few times thats proved pretty bullet proof over the years is a the limited duel method as follows.
Start off with a top up tank that is limited in size to offer a maximum of 3 days worth of top up at any one time. and set the RO unit up on a timed solenoid to top this tank up once every two days. then run your top up pump from this tank via double in line float switches (obviously making sure to avoid all the normal pitfalls of float switches, ie protecting them from snails etc) running two in series ensures that a stuck one wont lock on the top up.
Then run your Kalk stirrer from a peri pump that draws from your top up tank, on a timer so you can control the dose reliably over the 24 hour period....the more you dose, the less pure ro top up you use, and visa versa.
doing it this way offers you greater control over your kalk addition and your top up, plus the overal availability of water is limited to a volume that wont wipe out the system if something locks on.
again, my thoughts are with you, and hope everything pulls round.
all the best
Simon.