Should I increase my photovoltaic period?

I have a 37 gallon with four 18 watt t5 6700k bulbs. I've got some java fern started at the bottom of a piece of mesh, about 10-15 small plants. I'm dosing excel daily and CO2. I'm really trying to get this stuff to take off as quickly as possible.

Should I increase my photovoltaic period from 8 hours to 10 hours?

Or will this just grow algae?

Thanks!