Cyano problems are usually caused by aquarium water with excess nutrients like phosphate, nitrates etc. You can try and siphon out what you can to remove the algae in the short term. In the long term you may have to examine how you care for your tank. There are some commercial dry foods also contain excess nutrients and other undesirable things like nitrates, phosphates etc so I strain/rinse my fresh/frozen foods before feeding my tank. You may want to consider feeding your fish less often. Also, changing your photo period, bulbs, adding more flow and using RO/DI water all help. Adding a phosphate remover like Tropic Marin Elimi Phos and increasing flow in your tank may help too.