I have a lovely looking film of scum (??) that's chillin on the top of the water.... I can't remember if this happened to my last tank, but I don't think it did. 40g all-in-one open top aquatop. Tank is on week 1 of cycling so I am not too worried. Hoping it will go away eventually... Sand and live rock were put in Sunday (6 days ago) and that caused the scum to form. I have a sponge in the first filter compartment, the 3 little boxes have crushed live rock, bio balls and those small white ceramic cylinder things in them. Sock with carbon at the end. Thoughts??

