My school also has a Betta names Bolt. He lives in a 5 gallon Hex in the school office. I take care of his tank too. Today I cleaned his tank and it has a bunch of bright green algae that is super hard to scrub off. His light is on a timer and is on from 8:30 a.m. to 4:00 p.m. His water parameters are good, 0, 0, 15. I just did a water change and tried to scrub a bunch off with a tooth brush. Any ideas?