It is a wonderful little park under the west gate and the pinkness is due to stagnate water and PH changes which tend to occur in summer with long periods of no rain. A wonderful natural environmental phenomena. I thought they were died pink at one stage. I remember there used to be giant balls in the middle of the water and the myth was that they had fallen off the back of a trunk driving over the westgate bridge.
Thanks @melbourneswest Good to learn why it was no longer pink. I remember seeing this internet a few years ago, but I had no idea it was in Melbourne, and I wish I could see it someday. Sadly, I'm here now it's no longer pink. :)
Will check Lake Tyrrell next time 😀