Originally Posted by Readingexcalibur
I feel hijacked haha, now back to the OPs question haha.
Sorry Ex, felt obligated to answer!!
As far as lighted sump...I don't think it really matters. Bacteria are there, that's the main purpose of the rock, so I don't think light would really do much, besides more coralline algae. If you offset the light, like on a refugium, it may help with diurnal Ph shift, but only a little, like a refuge. Just my opinion, but I don't see much advantage to lighting it. Also with light, just another place to grow algae!