Yes, takes time. I'm going into my first algae battle of the season myself. (D'oh - I forgot to increase the filter run time once my water got up to a toasty 80 degrees!) It usually takes me about 4 days or so to get it "swimmable" again.

Did you have your solar cover on for all of those clear weeks? I apologize if this is old news for you (I learned the hard way last year) but you need to take to the cover off at least one day per week to keep the algae at bay. I don't know exactly why - whether the pool needs to breathe or the skimmer needs to operate properly or what - but it does need the break, and it's a good time to brush the walls and bottom too.