I did manage to sort the BGA a while ago, after faffing with liquid carbon in a syringe for a few weeks I just turned the light off instead and it buggered off pretty quickly.Hi @mrhoyo
It is not unusual for Cyanobacteria (aka BGA) to grow exactly as your photo shows. That's because Cyano need iron and this is more plentiful where there is less oxygen available - such as in the substrate. But, Cyano also needs light and, hey presto, it gets just that where light falls on the tank. Using a pipette, I inject a few drops of Easy-Life Blue Exit into the affected area of the substrate. This is usually effective in killing off the Cyano. Some people simply apply suitable tape to the outside of an aquarium to block the light but it's a bit of an eyesore.
Good luck and please keep us posted.
JPC
I started using CO2 about a year ago and that solved all my algae issues and the plants went mental. It ran out a couple of months ago and I haven't replaced yet due to the impending tank move. I'm assuming that's why I now have loads of BBA at the minute. We'll see when I get it moved.