Why am I getting this algae?

[jeepers]

I've convered to the BBB and since doing so I'm finding that I'm seeing algae. Please see the linked picture for a better idea of what I'm talking about. I get this about every four days. Vaccum it away and it's back in a few days. I never saw this when I was using the pool store method, although that's probably because I was shocking once per week on that regimen. I'm getting this around the perimeter (as pictured) and also in the creases in the deep end (25,000 gallon vinyl). Also, I've found that though it's not highly visible, I can stir up a cloud if I push the brush across most of the flat areas in the pool.



I have been on top of my numbers and check faithfully every day. CYA is about 60, I run FC usually between 7-9, CC always 0, pH steady at 7.6.

Thoughts? Recommendations? We've had lots of rain here in Philadelphia and I plan to shock after the hurricane comes through this weekend, but I'm curious to learn why I'm seeing this algae despite keeping up with my chemicals. Is this just par for the course and means that I need to bring the FC up to shock level?

Thanks.