Kalk Powder

[muck]

Anyone know if it has a shelf life? Can it become unusable?

[michika]

I know that if it clumps, or starts to get "gritty" its no longer good. As far as I'm aware, and have heard (http://www.talkingreef.com/forums/podcast-episodes/674-diy-kalk-doser-video-podcast-episode-44-a-2.html) its okay as long as it doesn't get wet, or absorb moisture.