Yep, I fill my pots to the rim with them. Couldn't tell you how much I use in each pot. The big bag of them will fill about 30 - 35 6"x6" pots.
Peroxide breaks down within 3 days, so you have to retreat with the peroxide every 3 days. Remember algae needs two things to grow: food and light. The peroxide may kill off the algae, but it will come back if you don't eliminate one of it's sources. Since you can't get rid of the food source, that means you have to block off the light.