Dead aglae

[blackberry]

How do you know if mustard algae is dead> I mean what does it look like after it dies

[chem geek]

Whereas green algae gets bleached out and turns gray from the chlorine (and is, at that point, killed), yellow/mustard algae doesn't have a big change in its appearance so it is much harder to tell. You need to shock at a higher level (around an FC that is 60% of the CYA level) and be sure to get behind light nichers and put in pool equipment (poles, etc.) that could be harboring the algae. Remove it via filtration and vacuuming with subsequent backwashing (a skimmer sock can also help, if the algae gets stirred up).

As noted in other posts, you may have pollen and not yellow/mustard algae. Yellow/mustard algae prefers to grow on the shady side of the pool whereas pollen will settle into dead circulation areas even if they are in the sun.