White things on walls after adding live sand

[Miami Reef]

I added a larger gain sized live sand to my 1 1/2 cycled tank last night, and there’s this white algae-like thing that is swaying with the water movement. What is this? It’s pretty difficult to scrape off.

 

[Big G]

How old is the tank?

 

[mtraylor]

Looks like your glass was dirty with some type of film or algae on it and you added sand to tank. Once all the smoke cleared and you could see in there.....the film/algae now has sand and dirt all in it.