does a DSB need light?

[rick12]

if i have a sump with a DSB does the sand need light to perform?

[papagimp]

Nope, in fact many keep them in darkenss intentionally. My DSB section in my fuge has all the sides painted black (krylon fusion-plastics) to keep light from reaching in through the sides. And the top of the DSB is covered by macro algae, so not verymuch light gets through very well, just a little ambient lighting.

But honestly, I really don't think it would make too big a difference, I know it does some, but not 100% on exactly what kind of difference. The bacteria that's doing the filtering (anerobic stuff) is deeper in the sandbed where there is no light anyways, just lot's of sand)