What is the action called when adding dechlorinator

[Essjay]

It is how the dechlorinator moves through the water

If you mean the way the dechlorinator molecules move through the water till they are evenly distributed throughout the water, that's diffusion.

 

[porl66]

If you mean the way the dechlorinator molecules move through the water till they are evenly distributed throughout the water, that's diffusion.

Yep thats it BUT there is a technical name for it also

 

[Essjay]

Diffusion is a technical name - it's the one used in chemistry to describe the movement of substances through a liquid, or one gas through another (when they aren't mixed by a human stirring them up)