Instructions
Remove chlorine from your tank. Plain tap water is fine for most fish, but if it's from a municipal supply or a holding tank, it probably has too much chlorine. Use a product such as NovAqua or Tetra AquaSafe to detoxify tap water for your fish tank.
Add an aquarium filtration system to your tank. Many types of filters are available, including sponge filters, bio-wheel filters, undergravel filters and fluidized bed filters.
Wait until your water has cycled before adding the fish. According to FishLore, the nitrogen cycle, which establishes helpful bacteria, begins when you first set up a tank. The ammonia and nitrate levels rise and then drop off as the good bacteria grow -- a sequence that can take from two weeks to two months. However, you can use fish food, pure ammonia or a filtration system that includes bacteria to speed up the nitrogen cycle.
Check the water with an aquarium test kit before you finally know that your water has been purified for your fish. Different kits are available for freshwater and saltwater tanks, and they can detect chemicals such as ammonia, nitrate, pH, calcium and chloramine.
How to Purify Water for a Fish Tank
The novice fish owner might not question how safe it is to simply pour tap water into his fish tank. However, to maintain the health and appearance of a well-kept fish tank, the beginner must consider the quality of the tap water before adding any fish. The bottom line is that you cannot put the fish into your aquarium until it is a safe, stabilized environment.