PondLith is a natural filter material based on zeolite. The zeolite is completely natural with a grain size of 5 to 10 mm. The fine pores and channels of the natural mineral store pollutants, especially ammonium. Useful microorganisms make use of this and support the bacterial degradation of nitrogen compounds in addition to adsorption. Thus, PondLith offers the ideal filter support during the run-in phase and deprives the algae of important nutrient resources. Depending on the load, the duration of effectiveness is approx. 125 days.