I have a 2.5 gallon too, get some cabomba, hornwort, guppy grass, dwarf hydro and wisteria. All the plants are rapid growers under high light and will help reduce the algae by using up the nutrients.
I suggest you do small regular dosing of excel, I do 3-4 drops a day and I find it helps the plants more and reduce algae then doing big weekly dosing. I think a big dose of excel might put too much nutrients in the water and the plants can't use it up, if you do small daily doses, its just enough for the plants to use and nothing left over for algae.
good luck! you tank looks really cool!