New to this group. We have a 24,000 in-ground vinyl pool with sand filter. Pretty sure we have mustard algae and we're following the slam/mustard slam directions from this site. After the first slam our FC hit 45 which is good per the chart. Checked at 2 hrs and down to FC of 6 so we added more 12.5% shock. Back up to 40. We left our auto cover open. Should we keep it closed during the day to lessen Chlorine loss from sun? We have been keeping our cover closed and we were worried this caused the algae growth. Our CYA is 55.