The beauty of tropical freshwater aquariums is enhanced by using decorations such as wood. The most popular types of wood used in tropical freshwater aquariums are bogwood, driftwood and Mopani wood. They can be purchased at a pet or aquatic store. All types of wood must be prepared for use by soaking to reduce the release of tannins into the water. Tannins are water-soluble chemicals found naturally in wood that migrate to the surface when immersed in water.
Bogwood is wood that has been created in a bog under anaerobic conditions and preserved from decay for hundreds to thousands of years. It has a long lifespan and provides shelter for small fish and other aquatic organisms. Bogwood is highly beneficial in freshwater aquariums because it is the least likely of all the woods to rot or contaminate the water with parasites. However, it must be prepared for using before placing in the aquarium or it can affect the water's pH levels and make the water acidic.
Driftwood is common wood collected from rivers, lakes and the ocean. Although driftwood can be used in freshwater aquariums, it is the least desirable out of all of the types of wood because it tends to rot and negatively affect the alkalinity of the water. Do not collect the wood yourself. Driftwood sold in pet stores has been prepared and soaked to remove bacteria and fungi. Do not use driftwood from the ocean in a freshwater aquarium. Ensure that the wood is aquarium safe and not intended specifically for reptile use.
Mopani wood is an exotic hardwood from the mopane tree in Africa. It is one of the hardest and densest woods available and comes in a deep, chocolate brown and light, sandy yellow with interesting textures and twisted shapes. The wood is prepared for use by soaking and sanding so it has a smooth surface. The Mopani wood can leach tannins for weeks or up to a year, with the first month being the worst. This can be alleviated by performing weekly water changes.
Using wood in a freshwater aquarium provides fish and other small creatures a place to hide from aggressive fish. Some species of fish will breed or lay eggs on or near wood. Fish may eat the wood and the algae that will naturally grow on it, enabling them to exhibit instinctual behaviours while supplying them with a healthy, natural diet. Wood provides surface area for beneficial bacteria to grow on, resulting in removing harmful nitrites and ammonia from the aquarium.
Regardless of which type of wood you choose to use in your freshwater aquarium, it will leach tannins for a period of time, requiring frequent water changes when you set up your tank. It can be difficult to catch fish, since they will use the wood to hide in. Uneaten food and fish waste can get trapped in crevices or cracks in the wood. Cleaning the aquarium can be a challenge. To properly clean the tank, you may need to remove the wood and use an aquarium vacuum to suction beneath the gravel.
Preparing for Use
All types of wood must be prepared for use before placing in your aquarium so that tannins are not released into the aquarium. Although tannins are not harmful to your fish, it will discolour the water, making it brown and cloudy. Soak the wood in a bucket of boiling water for one hour. The hot water makes the wood expand and releases the harmful tannins. Empty the bucket when the water becomes dark. Refill the bucket with boiling water and repeat until the water stays clear. Refill the bucket with hot water and let it sit for five to seven days, then change the water again. Repeat the process for one to two months.