I have been keeping the "artificial" light off but for 1-2 hours a day and I still am having probs with a hairy green algae. What should I do now ? I would prefer NOT using chemicals but if that's the only alternative which would be the best one for my 55gal aquarium w/ guppies, 4 different kinds of tetras, some oto cats, female betta and etc.? I would prefer that my nice golden snails also survive !