I also run my fuge on a reverse photoperiod...but, what is different in my fuge than most folks is that i have an enormous amount of xenia growing like weeds.....oh yeah..i have some chaeto in there too!
I run the fuge lights for 16 hours, but it gets a lot of light indirectly b/c it's close to my windows...so it prolly only gets close to 4 or 5 hours of total darkness
the growth rate of the xenia is explosive, to say the least....but the chaeto growth rate could be improved a bit...i'm only reaping chaeto every 2 weeks or so.... ideally, growth should be so much that weekly harvesting is required
i run my fuge light on my reef for like 20hrs, i turn it off for a couple hours at night so it doesn't light up the apartment so i can get some sleep. it turns back on early in the morning after i'm already asleep. its one of those screw in bulbs that is supposed to be the ultimate fuge light. my cheato doesn't grow very well, but its growing alot better now on 20hrs than it was on 12hrs or 16hrs.
i also have a tiny AC110 fuge on my 7g minibow, under 2x9w PC bulbs. the stuff grows like crazy. the light is on 24/7.