[rossb]

I was talking to Jonthan and he just added about 1 tsp per gallon to his top up water. I have a 60 gallon barrel I am using so I added a bit of powder to my top off (about 1/2 tsp per gallon). I have several polyps and Zoo's and, on the advice of a few locals, have taken to adding kalk. The kalk is to help with those. Would this be correct?

Ginku I use an activated charcoal from my LFS. I think it has to be activated and of high quality. The charcoal that you use for grilling would not work because it has several noxious additives in it. I would recommend trying it though...it does make a difference.