Sound like cyano and maybe diatoms. They often show up around 4-6 months.

However, they may be due to a nutrient problem. I would test your water parameters and manually remove the cyano and algae/diatoms manually with a fine brine shrimp net or via siphon.
Which Marineland filter? Canister or hang on back? Either way, do you change the filter media regularly (and if so how often)?
LED's should result in less nuisance growth, however, if your nutrients are high and are causing the growth, you still have a problem you should address.