Ett utdrag ur länken nedan, det är väl det värsta som kan hända att Ca:t droppar. "Why did so many earlier trials with Zeolites in seawater end unsuccessfully, even though they worked perfectly in freshwater? The answer is easy: The Zeolites commonly used in freshwater adsorb ammonium, which is a desirable function in fresh, AND seawater. However, Zeolites do prefer calcium. Now, you can imagine what happens in seawater! There is usually little to no calcium in normal freshwater, so the Zeolites absorb ammonium. Because there is a lot of calcium in seawater and because these specific Zeolites prefer calcium, the calcium values drop instantly, with sometimes catastrophic results. In the earlier days, when marine aquarists experimented with freshwater Zeolites, they ended up with very low calcium concentrations of less than 200 mg/l." Det här är en ganska bra länk som förklarar hur zeoliten fungerar. http://www.wetwebmedia.com/ca/cav1i3/zeovit/Zeolite_Filters/Zeolite_Filters.htm /Janne