Orange spots on the substrate....what is this??

I recently started a new saltwater aquarium and im just letting the tank cycle with three little 3 dot domino damsal's and two of the 3 stripe damsals, its been running for about 2 weeks total and 1 week with fish in the tank. i have very little amonia being a a new tank and 0 nitrate and 0 nitrite my pH is 8.3 so everything seems to be fine with the water. i have more than enough filtration in the tank and the protien skimmer is running smooth. I have done many tanks befor but this time i am getting these orange spots that dont seem normal forming on top of the sand. Has anyone seen or heard of this befor and know what is causing it?