According to the manuals I have, channel 21 just controls CMY speed. If you want to control dimmer speed, simply program a fade with the time you want using the dimmer channel.
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .