Weird. They use to be able to sell them separately. They still sell them in the US
http://www.premiumaquatics.com/Merch...&Category_Code=
But it seems overpriced. I think a Phosban reactor can do the same thing (after you modify the fittings) and has multiple purposes so if you ever stop using kalk, you can use it for its other original purposes (phosban, carbon, etc).