I appreciate the advice from this community to rid my pool of an awful algae bloom, but I registered to post that despite the popular opinion here, algaecide seemed to be the solution to my algae problem. Since this is all anecdotal, I would like the opinion of this helpful community.
My problem began after a 14 day vacation, during which my home endured thunderstorms and a power surge that tripped the circuit breaker to my filter.
I followed the SLAM guidelines and measured everything for my 27500 gallon pool with chlorox concentrate. I didn't have a test kit that measured to shock levels (it's coming), so I bothered my local pool store every other day to test. With a CYA of 41, my target FC was 16 and the morning tests never showed the FC below 8.1. After about 14 days of repeating this and $80 in chlorox, backwashing the filter twice daily, the water began to turn blue again but cloudy, but the FC kept drifting down due to more contaminants. I let the FC go back down to 3 again thinking that the worst was over and that the slight cloudiness was due to suspended particles from runoff. Silly me, as the green algae just came back.
I decided to buy dry shock and then an algaecide solution of 50% Didecyl dimethyl ammonium chloride, 10% ethanol. Maybe it was due to the overcast days, the dry shock, the algaecide, or the combination of all three, but the pool was back to clear again in 24 hours.
And I will be getting a proper test kit to test high FC levels.