Sometimes people will advise that I reduce the photo-period (duration of lights turned on) to help fight algae.
On the other hand, some of the plants I would like to grow demand for much more lights than I'm providing at the moment.
Will these light-demanding plants strive with a higher light output, but for a shorter duration ? I would like to add maybe 1 wpg on top of what I have (1.6-ish) but at the same time, don't want to end up with exponentially more algae...
You're better off with a multi bulb ballast that gives you power control over the bulbs so you can run more watts as a burst for 1 or 2 hours in a normal photo period. Lots of Co2 and ferts keeps algae away even with higher intensity lights. I run at 1.44 wpg with a 2.8 wpg burst for an hour.
While I don't keep plants,I know that the quality of reflectors used will make a huge difference in the intensity of light directed down.The old watt per gallon is no longer a rule of thumb depending on type of bulbs and reflectors used.