If you are over run by algae, to get ahead of the algae you could turn off all light and do the black out to kill the algae first. give it 2 days no light most algae will not survive this water change and voila! your plants should be fine during this time.
cut the light back to 8 - 10 hours, with 1 CLF you cant really vary the intercity of light, so you may just have to play around to find the balance. On one tank I had it could handle 8.5 to 9 hours. Over or under all hell broke loose.
there is a limit to how long plants can photosynthesis efficiently after that algae start to win.
If you want a real plant factory you need co2 which allows you to run lights longer & at higher intensities.
I never had luck with Excel at the needed dose it killed my fish, if you dont have fish or more hardy types it I hear works. In either case if you don't need the water movement try to cut it down especially at the surface.
best of luck