diatoms...(on the rocks/sand for sure) 100% NORMAL...
I can't tell if that red on your sandbed is the start of cyano or just poor color mixing from your LED fixture..
But its 100% normal to have diatoms/film & hair algae/cyano in a new tank..
It will pass provided you keep up with proper maintenance/low nutrients..
The diatoms will die off after free silica in the tank is consumed by them..