Alder cones will usually slowly release tannins for a couple of months. Eventually, they'll run out and end up as a great place for collecting biofilm. You can leave the cones in your tank forever, as they'll gradually break down and get eaten. The alder tree (Alnus species), also known as the common alder, black alder, European alder, European black alder, or just alder, is a native of Europe, Southwest Asia, and Northern Africa. However, now a days alder species are also in the US and Canada. The tree produces a cone-like flower and once the flower is pollinated, the flower turns brown and hardens into a ‘cone' which holds the seeds. Before using the alder cones in your aquarium, soak them in fresh water for one night to let them become waterlogged and to leach off some of the tannins. If you add the Alder cones directly in to your tank, you will have COLORATION. Starting with adding 1-3 alder cone per 5 gallon is safe. Once you understand the effect they have in your specific tank setup, you may be able to use alder cone per gallon instead. You should start slowly and carefully monitor your water parameters and color. There isn't a specific guideline for how many you should add to your tank. Always go slow when introducing any botanicals into your aquariums, so you can see the effect they have on your shrimps, fish and plants. Keep an eye on your pH level and the darkness of the water for a few weeks before you add more. Be careful not to lower the pH level too much and stress your shrimp. Alder cones will release tannins into your water, making tannic acid and lowering your pH level. This makes them very useful for tanks with Bee shrimp, as they thrive in more acidic environments. Water with a higher buffering capacity, or carbonate hardness (KH), won't have its pH level affected much. NOTE: Product is intended for ornamental aquarium or terrarium use only. KEEP OUT OF REACH OF CHILDREN.