how much shock is too much?

[waterbear]

1 gallon of ultra bleach will raise 10000 gal approx 6 ppm
1 gallon of regular bleach will raise 10000 gal approx 5.25 ppm
Call your pool 20000 gallons to make the measurement easier so I would add enough to keep the pool at about 12-15 ppm until the algae is gone.
another way to look at it is 2 oz of ultra bleach will raise 1000 gallons about 1 ppm so every 36 ounces (call it a quart to make it easer) will raise your pool just about 1 ppm or slightly less.
These are approximations but should be close. Test the water and make adjustments accordingly.
Hope this helps.