If you prefer your decorations to have a natural touch, driftwood, for instance, is an option for decorating your fish tank to match the rest of your natural décor. However, driftwood needs to be cured before it can be used. Curing removes the tannins, the biomolecules that can cause aquarium water to turn brown, from the driftwood and neutralizes any acids in it so that, when the driftwood is placed in your fish tank, the water does not become discolored and pH balance of the tank remains at the proper level for your fish.
How to Cure Driftwood
Scrub down the entire piece of driftwood using a stiff scrub brush. Avoid the use of soaps or chemicals and use water only. Rinse the driftwood thoroughly.
Scrub the driftwood one more time using non iodized salt. Rinse thoroughly.
Soak the entire piece of driftwood in a large non-metallic tub or bucket filled with water. Leave the piece of driftwood submerged in the water for a minimum of one to two weeks. This process will allow for total saturation of the driftwood. If desired, you may add a one pound box of baking soda to the water. The baking soda will help to neutralize acid and help sterilize the driftwood.
Allow excess tannins to be removed from the driftwood by leaving it to soak in the tub of water. These tannins will leach out of the driftwood. Tannins left in the wood may cause discoloration in aquarium water and can slightly lower the pH of that water.
Check on the soaking driftwood regularly. If the water becomes dark or discolored because of the release of tannins, empty and replace it with fresh water. Rinse the driftwood before placing it into the clean water.
Continue to change the dark or discolored water until it does not change color for several days in a row. When this happens, the wood has been cured.
Place the cured driftwood into your aquarium in the desired position.