When changing water for goldfish, it is not recommended to use purified water. Purified water has been filtered and refined, resulting in extremely low hardness and mineral content, which is not suitable for the growth of goldfish. The oxygen content in purified water is low. Long - term use may lead to a decline in the goldfish's immunity and even death.
The Best Options for Changing Goldfish Water
Tap Water: The most common choice, but it needs to be treated in advance. Tap water usually contains chlorine, which is harmful to goldfish. The treatment method is to let it stand for 24 - 48 hours or use a dechlorinator.
Well Water: It has a moderate hardness and mineral content, but the dissolved oxygen is low. Before use, it needs to be exposed to the sun or aerated to increase the dissolved oxygen and adjust the pH value.
River Water: It is naturally clean, but precautions should be taken to prevent excessive microorganisms and industrial pollution.
Rainwater: It has a high oxygen content, but precautions should be taken to prevent air pollution.
Precautions for Changing Water
Water Change Frequency: Change the water once every 10 days in spring and summer, and once every 15 days in autumn and winter.
Amount of Water Change: Each time, replace one - fifth of the water at the bottom of the fish tank to avoid a large temperature difference.
Control Water Temperature: The temperature of the new water should be the same as that of the original water in the fish tank to prevent the goldfish from getting sick or dying.