Too much light. you need to do lots of water changes and cut back on the light. Or since you have no fish or plants just black out the tank for a week or so. cover it so no light gets in. That will kill the green algae. Then do a big 80% water change and add lots of plants. Fast growing plants like watersprite That way the plant uses up all the plant food before the algae can.
Rinse the filter in some clean aquarium water too.