What color is the solution in your drop checker? (If you dont have one, this is your hint to get one)
you most likely have an imbalance in your co2 and lighting schedule.
you definitely have a shortage of nutrients.
fuzz algae (aka bba) comes around with fluctuating and/or low co2 levels. not the difference between night time and daytime co2. Do you have your co2 on a timer that is in sync with your lights?
What i would do:
8 hours of light/co2
obtain some dry fertilizer and dose according the EI method
make sure your drop checker turns green about an hour after your co2 comes on.
Remove plants/leaves that are infested.
''you definitely have a shortage of nutrients.'' <<< this might be it since Im barely getting the hang of fertilizing method.
