Natural sun light

[mrcoffee2]

My tank can get NSL up to 3hrs a day in the corner, if i move the curtain. I think this is pretty sweet and could be beneficial. Any downsides?

 

[Retro Reefer]

Corals love natural sunlight but the problem is so does algae..

 

[CodyRVA]

Possibly... possibly, algae, but this is only likely to happen if you already have high nutrients. I know many local reefers with systems that receive a lot of natural sun light and have no issues with algae what so ever. NSL is a great "natural" sunrise/sunset. Try a little bit of NSL at a time and see what happens; i'd progressively allow more light in until you have issues.