With no CYA, a lot of your FC is being burned off by the sun instead of fighting the algae unfortunately. Might want to really make sure the FC is up there at night so you know it is helping.
Is it liquid or powder CYA? If liquid, I am wondering if you can clean the filter as I think it disperses faster (although someone should confirm).
From you CYA comment in the first post, I was curious if you had already added some.
What size filter do you have? I am not too familiar with cartridges, but I did not realize they needed cleaned so often when fighting algae (although I guess backwashes happen often too) ... there is your motivation to prevent your pool from turning green in the future. :-D
Oh and I overlooked the fact that your FC was so high with regard to the pH ... the pH test is not valid for FC above 10, so it may not actually be that high. If it drops below 10, then test the pH to make sure you do not need to add acid ... did you do that before starting to shock?