What type of algae? Pictures would help to identify it as there are different causes that contribute to different types of algae problems. There are no need for chemicals as they are not good to use in tanks. The first step would be cutting your lighting down to only 6 hours a day. What size tank, what are you WC
schedule and how much do you change out? Also do you know your nitrate and phosphate readings? Lastly what type lighting do you have and how long do you run them daily.