– Release tannins into the water which help prevent bacterial growth in shrimp. – Acidify the water which will slowly lower the pH level – Shrimp will also eat the cone as it breaks down -Bio-film will accumulate on the cone which is another great food source for shrimp. – Ideally add boiling water and leave overnight and/or rinse before adding to your tank. – 1 cone for every 15l of water – You may add or replace as and when needed. (3-6 months) – For more information re this and other