Well, if u wana grow them fast, then use moderate to slightly high flow, to let the algae tumble and have less chance of detritus choking it.
If using PL lights, at least 36W to preferably 55W is best for growin these algae.
Timing wise, 24hrs may be abit overkill, i would prefer u used a reverse timing to yr main tank lights. Eg algae lights on 1/2 hr before main tank lights out, and then algae lights out 1/2 hr after main tank lights on. This shld ensure stable PH for yr tank water throughout 24hrs.
But of cos u will need a large enough amount of algae to do this!
Hope this helps?