Do you have enough flow in the tank? I found that re-arranging my rocks ( allowing more flowthrough teh rockwork) , adding another powerhead ( I have 3 koralia 3s in my 55 gallon) and doing a few water changes ( followed by weekly changes) helped my algae issue tremendously.
I wrote an article on the subject too that might help. More than likely excess nutrients are being collected somewhere in your system. 99.9% of the time thats usually the cause of algae.. just need to find where it is ( in an un-attended to filter, behind a pile of rocks etc)