Algae

[chenyi]

I've been frustrated by algae for years. I finally might have found the problem. I've always known that my tank was close to a big window, but the sun is not usually shining directly on it. Other people have windows, right? It can't be THAT big of a deal. The amount of algae I get is insane.

I realized today that my neighbor has a 6 foot high white PVC fence. I think maybe I never accounted for all that reflected light.

 

[Aiken Drum]

Ambient daylight in the shade. 10000 lux.
Inside light level at window. 1000 to 500 lux.
Inside light level at 4m from window. 20 to 50 lux.

The amount of light drops dramatically as you move away from a window. You might not notice it because your eyes are good at adjusting for light levels, but you can easily have 20x more light close to a window compared to being on the far side of a room. Download a lux meter onto your phone and take readings of your own.

You want aquariums on the far side of rooms away from windows.