As above you may be fine with an inch.. I'm mostly paranoid and try to avoid problems down the road.
Try starting with that, add some if you start to have green water or cloudy water issues.. and if you do, pull crypts and swords up (or similar) so the crown is not buried.
Try starting with that, add some if you start to have green water or cloudy water issues.. and if you do, pull crypts and swords up (or similar) so the crown is not buried.