Nice Job, LadyBug!

The shock you were using is nothing more than double-strength Ultra Bleach--one gallon gives you the same chlorine as 2 gallons of Ultra....Except that unless it's VERY new, it breaks down rapidly and probably was no more than 10%. Still, if 1 gallon of 12.5% is cheaper than 2 gal of 6%, it's a good price.

You were going to need a lot of chlorine no matter what you did, but the reason we push, push, and push the high-end test kits, like Ben's, it that they allow to know EXACTLY how much shock to add. If you add the right amount 3 times a day, it will be more effective than adding all 3 doses at once.

You did the big one--lots of chlorine and persistence, but to make it easier you test 3x/day and add chlorine until it tests at the shock level (I think 15 for your CYA level).
You brush and vacuum to waste everyday, too.

It kills the algae and less chance of bleaching the liner. But I think Dave is right--you had SO many organics that the chlorine was being consumed very rapidly.

Enjoy your pool! Now stay ahead of it and NEVER have to do that again!