What Type of Water Should You Use in Fish Tanks?

Water is a major part of every fish's life as it provides their environment, oxygen and hydration, among many other roles. When choosing and preparing water for your fish's aquarium, the most important element is understanding what kind of water your pets naturally live in and require, and recreating that water with its specific characteristics.

  1. Alkaline

    • Alkaline water is necessary for some species of fish including African cichlids. This water is generally characterized by having a high pH, around 7.8 to 8.3, and a high concentration of mineral salts, including calcium carbonate. Start with a neutral water source, which can be purchased from a market or pet store. Treat it with a dechlorinator and add either an alkaline buffer and mineral salt or calcerous rocks. These stones might include crushed coral, oyster shells or tufa rock, all of which can be recommended and purchased from aquarium stores.

    Soft Acidic

    • Many freshwater fish in the ornamental fish trade will thrive in soft acidic water. These fish include discus, angelfish and tetras. This water typically has a pH level around 6.5 and a general hardness of 5 to 10 dH. Soft acidic water is more challenging than alkaline water to make because it's harder to remove minerals from water once they've been added. To prepare this water, collect rain water and run it through a carbon filter or use a reverse osmosis filtration system on tap water. Add bogwood or peat moss to help lower the pH levels.

    Brackish

    • Brackish water is created naturally when marine and fresh waters meet. Fish found in brackish waters include archer fish, scats and monos. The characteristics of brackish water vary from regions and throughout the seasons, therefore making it difficult to define a standard. However, its pH level should remain between 7.5 and 8. To create brackish water for your aquarium, begin with neutral water. Add marine salt to create a salinity of 1.010 specific gravity.

    Marine

    • Marine water, or saltwater, hosts many fish found in the sea. These pet fish include clownfish, butterfly fish, gobies and wrasses. Marine water is characterized by a pH level between 7.8 and 8.3 and a specific gravity of 1.02 to 1.023. When creating this aquarium water, begin with a neutral water source and add aquarium salt according to the manufacturer's directions. Thoroughly stir the mix.