ActionScript 3.0 :: Keep Track Of Visible Shapes In An Array?

I am creating circle shapes with timer (currently with 40 ms delay) so every second it creates 25 circles, it then tweens few of their properties.I have left just the alpha which is important (for simplicity) .On the complete of each tween it tweens each circle's alpha back to 0, and then removes each circle from the stage.

so after I stop the timer, i can still see 20/30 circles on the stage for about a second until they dissaper.I wanted to push those circles in an array so that when I stop the timer, I put all visible circle's alpha to 0, or just remove them all together, so that they immediatelly disappear from stage.

but I also need to remove those circles from array which have already disappeared, so that I always have only visible circles in an array. (not million of them)(notice that tween time is math.random for each circle)

how could i remove them from an array in the same timer event?[code]...