With all that said (my last comments for now ... promise
), there is a good reason to go with RDP (reverse-daylight photoperiod) and that is as Jonathan pointed out for pH control. My comments only apply to "whether it has an effect on caulerpa going sexual or not." If faced with a choice of 24-hour vs. RDP I myself would go with the RDP (but that's just me ... for one, I find my electricity bill is high enough with just 12 hour photoperiods ... 24 hour photoperiods is a place I do NOT want to go!!!
)