How to install internal overflow on established reef tank

[sphelps]

You could buy or make black acrylic overflow boxes then use the bulkhead to hold them in place, no silicone or glue required. You'll need to drill a hole in the overflow box in the right spot for the bulkhead then get an extra gasket. Install: bulkhead - gasket - overflow box - gasket - glass - nut. Or use reverse the bulkhead with flange side on the outside and use only one gasket: Nut - overflow box - glass - gasket - bulkhead. Make sense?