Can you increase the distance betwen the lights & the tank and lower them gradually? I think that would be better than a short photoperiod. Also, I have heard folks using several layers of widow screen (between the tank & lights) & removing one every few days - or eggcrate, just something to difuse the light.

Also, 96W isn't giving you 4X the "amount of light" than your old 24W, it's just costing 4X as much to run them :grin:
It is considerably more light (2X+), but not 4X.