Yep. Add liquid chlorine and then brush to stir it up. Typically we say to add 5 FC worth on a daily basis until you can properly/fully SLAM and kill the algae.
 
We opened our pool this pass weekend and have filter problems. While we are awaiting parts I am staring at thus green cess pool. Is it OK to add chlorine without the pump running?
You can also scoop out junk that’s on the bottom early and it’ll help the process later.