Crush coral. So much easier to clean and my copepods love it and bred cause they have so many places to hide. My red coris wrass who is now about 7 inches amazes me that he will dive under the crushed coral and stay there for hours then when he emerges copepods are in the water everywhere for a feast for all. it is also better to have crush coral bed because I don't have to worry about wave pumps blowing sand around. When I vacume the crush coral I wait for the copepods to surface in the water that was sucked out then I put them back in the tank cause there are so many of them. Never had that with other tanks i had in the past that had sand