I'm relatively new here so I can't address the issue very well, but will say it does take some time after an algae outbreak to get rid of the cloudiness. We have a four foot above ground pool and even after shocking & killing the algae we battled last year, it took a number of days for all the dead algae to filter out. However, our pool is only about 5000 gallons & only has a filter cartridge. It took a few days to become swimmable, I think.