Originally Posted by E-rock
Could you use water from a water change to fill a quarantine tank?
...is clean water. New, clean water. As I said in the prior post, when you are quarantining for a short time, cycling is not an issue. The water volume you use should be enough to hold the fish without going through the ammonia cycle (which usually takes about 4-7 days to begin. Most meds you will be using suggest a 25% water change after 2 or 4 days during treatment. )
When you are holding a fish for longer periods, this is no longer a "Quarantine" tank, it's a "Holding" tank and should be set up biologically just as you would your main tank.
Either way, your fish need clean water to be healthy. Water from a water change is not clean.
Hope this clears things up