The present invention relates to a method for preparing a gel block comprising the following steps:—providing an alginate and calcium carbonate preparation (S1),—providing a buffer solution (S2),—mixing (E4) the alginate and calcium carbonate preparation (S1) with the buffer solution (S2) using a mixing tee comprising an outlet duct, and subsequently,—gelling said mixture in a gelator formed by the outlet duct, and/or a duct connected to the outlet duct, to form a gel block.