White sediment in sump

[Reef Devils]

This is my first saltwater aquarium and it is 2 and half weeks old. No fish yet. In my sump there is this white sediment in the corners and by return pump. I touched it and is did not feel like sand.

 

[Stephen8169301]

Are you able to get a closer shot maybe scoop up outside of tank in a small container with a dark underside to see it more clearly