Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Most people rinse before using it, then plant before adding water so there is less disturbance. Then fill by placing a plate or plastic bag over the substrate and pouring the water in slowly so it seeps into the substrate.
There may still be a bit of mistiness, but no big cloud like you are seeing.
At this point there are 2 ways to go.
A) rinse the material still in the tank by doing a continuous water change.
B) remove the material and clean the tank, and rinse the material outside the tank.