The koralias are specifically made to move alot of water, only cicrculation pumps I have ever seen are the maxijet ones with the attachment and they dont move as much water. You want the liverock to be the filtration and to do that you need very good water flow. You also dont want any debris piling up anywhere in the tank on the sand so the powerheads will keep that from happening if they move enough water and are angled correctly.
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.