how can i reduce the lighting for this setup

[Momotaro]

Neat idea PlantView, and welcome to the board!

Mike

[anonapersona]

Originally Posted by PlantView

Anyhow, I thought I'd just note that in order to cut light output it can be worthwhile introducing a flat piece (sheet) of household aluminum window screen between the light source and tank.

PlantView

Super!

That is just the answer I am looking for. I will be setting up a planted tank in an elementary school and will need to lower the lighting for experiments.

I assume I can use two layers of aluminum window screen if I need more dimming.

That's great, thanks!

[PlantView]

Originally Posted by anonapersona

I assume I can use two layers of aluminum window screen if I need more dimming.

anonapersona, yes, no problem. However the second screen should be rotated (cut and placed) at a ~45 degree angle relative to the first. Likewise, if a third screen is used it should be rotated ~15 degrees (relative to the first).

This is necessary in order to moderate the severe interference (moire) patterns that occur when regular, repeating geometric patterns are overlaid. If two (or more) screens with identical angles are stacked, the combination would exhibit a kind of "in-phase, out-of-phase" behavior that would make final positioning a critical and impractical exercise.

PlantView