Sunny:

The rules haven't changed. Lots and lots of chlorine, and lower your pH.

Your TA is 30, not 300. That's low but not an unusual #.

Don't worry about it now--get your pH down to 7.3 first.

If you have a really thoroughly algae-infested pool you have no choice--you are going to have to use the time-tested fight that may WELL take 2 weeks. I just spent $17 on a carboy (5 gallons) of 12%--which usually tests at 14%. That means 1 gallon of that will raise your pool's FC by about 10ppm. (I'm figuring you have 13,500 gallons). That's like paying $1.45 per gallon of Ultra Bleach.....a really good price!

The time-tested method:
Keep your pool at shock level (depends on your CYA level)
Check this 2 to 3 times a day
Keep your pH in the normal range, preferably at the low end.
Vacuum to waste once a day.
Brush the walls and floor once a day.
Keep at it.