Any idea what this is?

[Miamialum620]

Still pretty new to reefing and have this carpet like film building up along the sand bed. Don’t know what it is and how I should go about cleaning it.

 

[ndrwater]

That's Cyano. It's actually a type of bacteria. Manual removal, maintaining a managablma level of Play, and having decent flow help to keep it at Bay.
Part of the "new tank uglies". If it persists for a extended period of time (months, not weeks) there are a few products but there line ChemiClean that can be used to rid yourself of it.
Be warned though, things like ChemiClean can adverslad affect a new tank and the cycle.