StabHi Plus Organic Substrate ideal for tanks and ponds to add too or replace some of the biotubes, bio balls or bricks. Use StabHi to both act as an substrate for biological filtration and a source of carbonate to counter "acid creep" (the process of acidification due to nitrification) automatically while adding calcium. Every pond should have a bag or two to help stabilize the pH and supplying essential minerals. StabHi Plus is treated and baked for 24 hrs for a longer life and permanent filter media. Works well to fill one tray in a bakkie shower. Specifications: I kg or 0.9 litre provide about 0.68 m2 biological active area.