Catappa leaves also known as Indian Almond Leaves (IAL) come from the Terminalia catappa tree. They have chemical healing properties which may naturally help to fight off mild bacterial, fungal or parasitic infections. When Indian Almond leaves are immersed in water, the tannins and humic substances are released, which can lower the pH of the water. And will tint the water a rich brown ‘tea’ like colour as they break down
For more reading about effect of Tannins, you may want to go to:
Direct usage: The leaves will normally float for 2-3 days before sinking. Sinking is natural and it doesn’t mean that you have to change the leaves. Depending on how actively your fish tries to destroy them, the leaves will normally disintegrate after a month or so. There is usually no need to change the leaves more often than every second month.
Dosage: Serve as guide only – 1 leaf (size between 18 to 22cm) for 25 Litre of water.