Commercial algae killer is not good to use in planted tanks. You need to provide some information so advice can be given. What size is the tank? What kind of lighting do you have and how long do you run it daily? Is the tank planted? If so do you use ferts? Do you use liquid carbon or CO2? What are your nitrate and phosphate readings? Also a picture would be helpful so we know what types of algae you have.
Algae is usually caused from running too much light too long daily along with an imbalance of of lights/CO2/ferts. When you have algae issues you need to start with running your lights 6 hours daily max. Some types of algae can be spot treated but the problem needs to be addressed so the algae won't return.
