Hi Felipe,
If the normal spread is 9 and you want to stop trading if the spread gets to wide you might want to set the max spread to 1.5 to 2 times the normal spread or 13 or 18. Its really your decision as to how wide you will let the spread get before you stop allowing the robot to place trades. The other option is to just leave it at 0 which will disable this function.
Alan,