It isnt a big deal. Try getting some algae eaters if you dont already have some and cut dow on the photoperiod a bit. Otos, nerite snails etc are good options to combat algae
Sent from my iPhone using Aquarium Advice
How long are the lights on? What type? Do you dose ferts? Glut? Do you like oreos?
Sent from my SAMSUNG-SM-G900A using Aquarium Advice mobile app
Could just be diatoms. Does it rub off easily and crumble?
Sent from my SAMSUNG-SM-G900A using Aquarium Advice mobile app
If it is diatoms or soft algae nerite snails will eat it all over night if you get 4-5.