That's the reconditiong anti-sulfation pulse light. It is not needed to insure your battery is FULL. You may see it come on automatically if you leave the charger connected for weeks at a time but light 7 is as far as you need to go with this charger.
But...since you seem to be most concerned about sulfation rather than bulk charging....Run the Recond program
manually a few times a year (stirring things up at 15.8V briefly)... couldn't hurt and you'll get to see the red light work!