10.5 hours is not too much light generally. Brown algae often shows up during a tank's cycling. Brown algae require less light than other types, so excess light is unlikely to be the problem.
Let's start with some questions...
How long has your tank been running?
Have ammonia and nitrite levels stayed constant (0)?
How often do you do water changes, and what percentage?
Do you vac the gravel when you do changes?
What are your nitrate levels?
Does your tank receive direct sunlight at any time?
Brown algae tend to proliferate when there is silicate in the water in addition to phosphate and nitrate. Have you put any decorations or rocks that may be leaching silicate into the water? You may be able to get silicate adsorbing resin for your filter, but i don't know anything about whether that is a good or bad idea.
Introducing plants, increasing (!!) the intensity of the lighting, and increasing water changes are the things that might help short of adding fish (otos or plecos).
Let us know about the questions I've asked, and we might be able to get a solution!
