You need minimal swell for a couple of days at least to allow the particles to drop out and settle. Swell will also kick up sand around the rock structures that are most interesting when the water was already clear. Perth is quite difficult. Although drop 40 meters and it will be clear as!!!!
Here is a little trick but don't tell anyone!
Have some thin rope just a little longer than the depth you are diving, with a shackle or similar weight attached. Have it attached to a bouy at the other end with a dive flag so the boats can see you.. Lots of boats in Perth. When you dive down and see something you like drop the weight. This allows you to breathe up and dive down again following the rope and find the same spot amongst all the murk.. Which would have been impossible before.
It takes a little practice but you can get the hang of it.
All ways spend three times as much time on the surface as you do under water to prevent shallow blackout. So use a watch. If you don't understand this shallow water blackout you should do some research..
Good times have fun!!!!!
