When we see the dirty water in our aquarium, we would have immediately thought to remove all the water in the aquarium and replace it with a new clean water. But it really is a big mistake. When we replace the water aquarium with a new one then when we put back the fish into the aquarium there is a chance the fish could not adapt to new water conditions and fish will die.
The proper way to replace the water in the aquarium is quite half our waste, then we fill half of it with new water to avoid extreme changes in water conditions for fish to adapt. If the water looks still dirty then wait again the next day and replace the water aquarium in half, and we repeat this step until we are sure that the water is really clean. Sometimes the fish fast enough to adapt to environmental changes, so this should be so we pay attention.


