"Dosing with light"... interesting way to think about it! Normally though, "dosing" refers to the addition of some chemical additives... just FYI. 10 hours is not too long for lighting. With power compacts, I wouldn't run them any less.
Regarding the brown algae, it does sound like diatoms. If you don't have any snails like astrea or trochus in there yet, you probably want to add some now. They will help munch away on the stuff, and the other algae that will spring up.
You say your parameters are "great", why not post up those numbers - some folk's "great" numbers sometimes aren't that great, so it's good to rule that out right in the beginning.