Green Algae, now cloudy

[mbar]

Yes, you can add it everytime after you backwash - because the DE will backwash out of the filter when you backwash.

[Watermom]

Premix it in a little water and then just pour it into the skimmer while the pump is running. You only want to add enough to make your filter pressure rise by 1 psi. Wait 20 minutes or so after the first dose before deciding if you need to add more.