Only one of my four tanks does not suffer from algae, namely the 620T, presumeably due to the fast growing Elodea (Canadian Pondweed) floating on the surface for the benefit of my two Afican Butterfly fish in there. Fast growing plants will out-compete algae for nutrients in the water, providing there is enough of the plant, the trick is finding one that suits your tank setup (I tried a load of "Red Root Floater" from "voo" on the forum, but it has a strong dislike to water curent).