I have a generic, yellow flood light from Lowe's right over it.
Basic parameters I check: CA 460, ALK 8, MG 1200, Nitrates 0, pH 8.0, Temp 79-81
No invertebrates at all... just some live rock.
Definitely not caulerpa... it is chaeto (bought it from RCA and Aquadome)... it is all gone now... but it was slow over time until nothing but a few small strands....
Do I need more nutrients for my corals in my tank?