This action runs when any user requests to join a closed group.

 do_action('profilegrid_join_group_request',$gid,$uid);

Simple example

function profile_magic_action_on_join_group_request($gid,$uid)

{

//do something with the user id and group id any user requests to join a closed type group.

}

add_action( 'profilegrid_join_group_request', 'profile_magic_action_on_join_group_request');