Yesterday, for an experiment, I left the light off all day in the hopes that would further weaken and discourage the green nuisance algae in favor of the red algae and the Halimeda. The tank looks fine this morning. I’d like to think there’s a little less of the fuzzy green algae, but I can’t really say since it was declining anyway. The important point of this is that a day without light does not seem to have hurt the algaes I like.