Without any cya in there, your cl level is going to fall back down pretty quickly anyways. Go ahead and add some tomorrow. Add it to the skimmer while the pump is running and then wait a week or so to allow it plenty of time to dissolve in the filter before you retest for it, add more or backwash. Shoot for a reading of about 30. 30-40 is a good level for most people. For the next few days until your cya starts showing up in the water, you'll have to watch your cl level pretty closely to make sure you keep a cl reading. Don't want green water again.

Watermom