The tubing wears out when used with kalk, mine did not last too long. I also find the tubing gets deformed from the rollers, making the dosed volume change over time.
I had the aquamedic set up with a kalk reactor and worked fine (although I am generally not a fan of aquamedic). I posted if for sale a while back as I got the Tom aqualifter which pumps a little faster and suits my needs better.