Ok, I just installed my new hang on refugium on the nano. Everything is working good except for the return bulkhead leaks like mad! All it is, is a hole in the acrylic with a PVC bulkhead that goes through it and the back half of the bulk head screws onto the front half, with the acrylic pinched inbetween. What is the best way to seal this spot? Goop, aquarium silicone? Help me out. Once I glue it into place I suppose it's there permanently too. Thanks, DIRT