The non CO2 level of that type of light without getting algae problems is one of those shades and they usually have a 13W bulb. With the CO2(which I'll presume to be DIY)
may be OK/w 2 of them, but also could by why you got that algae problem.
Like there are a couple of house plants which can doc well inside without direct light
from the sun so I can't completely discredit it. But green water/GSA/Hair algae and
that type which looks real close to it but is more wiry than slimy...they pop up
easily with direct sunlight.
Most of the feedback I read on here suggest better ferts to get the plants growing better as the main remidy for algae. Another thing about algae is it usually takes
prolonged periods of light to grow.
IF your objective is to increase the plant growth, I'd work on learning more about ferts
first. Light does drive plant growth. But they need complete food to go/w the light.
We tend to look at people eating all sorts of stuff which doesn't always have good food value and not seeing them have issues...but these plants are continously growing and
when one nutrient runs out in the tank, the plant can't grow past that point.
I would suggest reading this and then see what you think.
http://www.plantedtank.net/forums/showthread.php?t=107303
I've heard that the type of sub you have can be short on one or two nutrients.
It has some of them but not as much as the plants(depending on which kind) need.
AND for example Anubias and Java Fern take nutrients from the water, not the sub.
And that sub doesn't have enough Potassium for Wisteria(possibly, perhaps likely).
But see what you think about the info on that link.