Use your OTO kit and test it yourself using the dilution method from post#12. That way you'll be able to go higher than 10ppm with the testing.

See what happens overnight like I explained above. I have a feeling it may not be algae, especially with a CC reading of 0.

7.8 is the outside of the recommended pH range. You test it with your kit and see what you get. (BTW -- What is the highest that your pH tester will read?)

If you lose no more than 1ppm of chlorine from sundown tonight until within 2 hours of sunrise tomorrow, it is unlikely that it is algae.

Run the pump 24/7 while you are trying to clear the pool.