I agree that a good cleaning crew should help out a lot, but you should look into solving the problem, not just staving it off.
Test your phosphate and nitrates. Both of those should be undetectable. Make sure that you are also putting your lights on at the same time each day and for no more than twelve hours. ten hours a day is probably better if you are having an algae problem though.
Check your carbon dioxide saturation as well. To do this, get a bucket of tank water and put a airstone in it for 24 hours. You then test the ph of the bucket and the ph of the tank (try to do this about midday). If the bucket has a ph higher than the tank by 0.2 or more, then you probably need more water movement in your tank.
ps- I am sure you know this, but just to be safe: use only reverse osmosis or distilled water for topoffs and water changes.