Cloudy water in QT

[Timurrrr]

Hi. My qt tank gets cloudy the next day even after 100% water change. I am not an experienced aquarist but my previous quarantine setup did not have such problems.
It looks like some kind of small dust particles and gets worse until I can’t see anything and I replace water completely every 6 - 7 days. This is the last week my fish stay in copper. However I am tryin
g to understand if it is normal. I have bio balls and filter floss for filtration. Vi

Thank you

 

[mann1139]

How long do you mix your SW for before adding? Is the new water at temp?

 

[Timurrrr]

I mix it for an hour or two as per red seas recommendation and always match temperature.

 

[mann1139]

How do you mix?