I have the same above my 55 gallon (about 5" above the surface) but the difference is that I am hi tech. I would get a piece or two of window screen and put that between your light and surface. Also I would bump up the water changes to once a week if you can until you have everything figured out. Also drop your photo period down to 4 hours until you have things sorted out. Other than that just keep cleaning the black brush algae out as best you can, cut off leaves that are too far covered. One proactive thing you can do as a stop gap measure is to treat the tank with excel (you can get gallons of metricide 14 for way cheaper than excel) work up to the full dose over a week or two and even dose heavier if your fish can take it. Also get a syringe and some hydrogen peroxide and treat the bba directly (turn off filters while doing this and move your fish to a holding tank do a large water change after). For the gda and diatoms just leave them be and it will go away in a few weeks.
As for plants stick with slow growers like java ferns and anubias they will not strip the nutrients from your water column as quickly.
As for plants stick with slow growers like java ferns and anubias they will not strip the nutrients from your water column as quickly.