Excel is usually only a good remedy for certain types of algae like staghorn and sometimes BBA. The most important thing is to be consistent (I dose Excel every day), and have a complete fert regimen going so that the plants are getting everything they need to starve the algae out. I use the whole line of Seachem plant supplements, and I've been very happy with the results. It's not as expensive as you might think, despite needing about 6 bottles of stuff for a 30 gal. tank, but I only have to buy those bottles once a year, so it's not so bad. For larger tanks, you might look into bulk dry ferts and invest in a pressurized CO2 setup.