From The Aquarium Wiki
The difference between a well planted aquarium and a stunning display lies in good aquascaping. This is not just a matter of placing décor in the right combinations and places, it means being creative and using your imagination. Be careful what you put in your aquarium, as some materials may not be suitable. Decor should be bought from an aquarium shop, and not collected from the wild if you wish to be sure it is safe to use. Clean it without soap or detergents. Always rinse décor well before placing it in the aquarium!
Most rocks are suitable for an aquarium and won't have any affect on the environment, but some are calcareous and will affect the water by releasing calcium and carbonates, causing pH and water hardness to rise. A way to test this is to put a few drops of vinegar on the rock. If it fizzes, do not use the rock. The fizzing is caused by the acidic vinegar reacting with the alkaline substances in the rock, similar to the reaction caused by vinegar and baking powder. The alkaline substances will raise the pH and water hardness.
In a planted aquarium, rocks can be both practical and aesthetically pleasing. Smaller rocks can be used in the foreground, making open spaces look more interesting and creating gaps between smaller plants. Larger ones can be used as a centrepiece or in midground. Porous rocks can be used as media for plants such as Java Fern, Anubias species, or Java Moss. Do not use metallic rocks or rocks with any ore as these can change the pH, or pollute the aquarium, potentially being harmful, or even deadly, to the fish.
- Coal can be used in an aquarium once it is washed.
- Granite pieces can be used in individual pieces or can be stacked to form arches. Is it is best only to use granite from an aquarium retailer as a few varieties may be harmful to fish due to slight radioactivity.
- Quartz is a nice rock with an interesting colour. Place it carefully as it is sharp and can scratch the glass. Does not age well in aquariums.
- Slate is cheap and popular and is available in various colours from green to purple, but be cautious as it may have sharp edges.
Normal wood can not be used in the aquarium because it will cause fungal growth and will rot quickly. Bogwood can have a striking appearance in an aquarium and won't do any harm to the fish and plants in the aquarium.
Bogwood from aquarium retailers is safe to use without any treatment. However, it releases tannins and humic acids into the water, staining it a light tea colour. Depending on the concentration of tannins, it may make the water a light yellow to dark orange colour. This is won't do any harm, and is beneficial to some plants and fish, such as tetras, which live in that environment. It will, however, slightly lower the pH. To prevent staining the water, the bogwood can be cured in water for a week or two. Using activated carbon or some other similar media will get rid of the colouration, but will also remove some nutrients important to plants.
Brushwood is a term for twigs and other dry dead wood. This can be used in the aquarium, but make sure it is fully dry and not rotting. Brushwood contains fungal spores and is prone to rotting when it is wet. If it is placed in the aquarium without treatment, it will rot, and produce slimy bacterial blooms. Boil it for an hour or more before putting it in your aquarium. Do not use pine or softwood brushwood, as the sap is harmful to fish. All of the aromatic woods contain toxic, volatile oils known as phenols. The best woods for the aquarium are from fruit bearing trees (apple, pear, cherry, walnut, oak etc), anything 'sappy' (ie pine, cedar, beech, maple, sycamore) has high contents of phenols and are toxic to most life forms in some respect (it has been proven that pine/cedar shavings cause cancer and liver damage in rodents). That is why pine is used in furniture and cedar is used to make moth-proof closets and chests.
Synthetic Decor can be used to cover up filters, airstones, and other equipment in the aquarium. It may, however, be more expensive than the real thing. Once a slight growth of algae appears on it, synthetic decor can look quite realistic. Fake cork bark can be used to cover up filters. Synthetic bogwood won't rot or change the pH. Fake rocks won't release calcium and carbonates that calcareous rocks might.
Creating a Design
Creating a design is an important part of aquascaping. A beautiful display can be achieved if you have the right materials provided to lay out your design. Sketch out a rough design on paper and create a budget. Write down all the materials you need and their costs on a sheet of paper and find the total.
The results are always better when you plan ahead. Make a sketch of the aquarium with the decor, plants, fish, and all of the equipment, such as the filter and heating. A good idea is to have a centrepiece, or main focal point, in the aquarium. Make sure that the environment you want to have in your aquarium will be suitable for your fish. Remember to use your imagination.