Natural sunlight I think is the reason for it.
My other tank I'd positioned where it receives an influx of sun light and the green algea grows rapidly.
In my big tank I never used to get much growth compared to the other tank.I added some branches from the tank shown above and it seems to have spread.
The other thing I have noticed is I get a lot more green algea growing on the Apple tree branches than I do on the oak ones.I don't know if there is any reason for that or just coincidence.
My other tank I'd positioned where it receives an influx of sun light and the green algea grows rapidly.
In my big tank I never used to get much growth compared to the other tank.I added some branches from the tank shown above and it seems to have spread.
The other thing I have noticed is I get a lot more green algea growing on the Apple tree branches than I do on the oak ones.I don't know if there is any reason for that or just coincidence.