Light control in sump/refugium

I'm re-configuring my sump to be simpler and more efficient. I've put together a basic design I like and now I'm considering somehow blacking out the baffles on either side of the refugium to minimize light spillage into other compartments. If the sump were acrylic I would just use opaque acrylic for those baffles, but it's all being done in glass since acrylic doesn't actually bond to silicone.

Is there a good paint product out there that will stand up to saltwater, UV, and not harm the water chemistry? Anyone else have any experience?

75G Sump Design

Good point. My tanks has a plastic corner overflow itself. However, now that I think about it, it may not be a perfect seal, which isn't really a problem for an internal overflow anyway. Not too much of a problem for a sump either I suppose.

I don't know, I think glass may end up being less expensive so I may just not worry about blocking light through any baffles...