All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Chlorine is pure, not impure, as in principle all things are pure (unless proven otherwise). If the water in the swimming pool is as much as mentioned by the questioner, and nothing of its three characteristics, i.e. color, taste and smell, changes by the chlorine that is mixed with it, then, it is pure and removes the impurity of anyone performing Ghusl in it.
However, unless the water of the swimming pool is flowing or renewed, then one should not perform Ghusl in it, for performing Ghusl repeatedly in the water while remaining stagnant makes it filthy, which might spoil it for the people. The Prophet, sallallaahu ‘alayhi wa sallam, forbade performing Ghusl in the stagnant water which does not flow.
For further information, see Fatwa 90153.
Allaah Knows best.