I'm guessing your tank is somewhat new? I have the same thing happen everytime I put more base rock in my tank. It will fade away on it's own from my experience. After it goes away I bet the rock looks more like "live" rock. It seems to be a starting point for the rock to look more natural. Just my opinion though.
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.