Grey layer over my live rock

[Sathish]

hi all , I’m a beginner in reef hobby and its been 5 days after my first reef tank set up and my live rocks started loading some grey layers and it spread very fast even over the sand . It looks to me some kind of fungs. Can some one look into the image and advice me please.
Tank - 150 gallon
Live sand and live rocks loaded

 

[Aquarian]

That looks like Diotoms, at 5 days your tank should be just starting to cycle. Have you tested for ammonia yet?

 

[Becky]

Welcome to the forum @Sathish :)