[smokinreefer]

IMO this will not work effectively unless you have something stirring the kalk, or if you frequently change the kalk, or put very little kalk in at once.

i did a passive reactor, much like what you described, using an empty Tap Water Purifier. i tried this to try to alleviate some of the work involved in mixing and dosing every other day, so the only way this would prove successful for me, is if it could handle enough kalk that i wouldnt have to continually clean/refill it. so iput more than an inch of kalk in the housing. needless to say i ended up with kalk paste.

I do have a DIY kalk reactor now, but the design does need to be improved.

IMO you need a reactor that can effectively stir
all the kalk in the reactor.

HTH