Safe paint for a small section inside refugium?

[BigMikeFlipz]

Anyone have any safe paint, acrylic paint, etc. that can be on a small section inside my refugium? Looking to find if there is any safe paint for a small 1" by 10" section inside my refugium that light bleeds into my tank. It is a small HOB fuge, and the area is the overflow and light bleeds through that into the tank at night. I am really not looking for alternatives, unless it is something that will cover the space under water, and stay in place. My last ditch will be buying a piece of black acrylic to try to silicone in place, but really want to not add that to the fuge.

 

[exnisstech]

Years ago I used krykon fusion spray paint on some white pvc. There may be other options now.