Overflow replacement help

[danschargers21]

I have an 40 breeder up and running. Installed the overflow too low and have the waterline 3/4" below the plastic rim and it's bugging the he'll out of me.
Got a new overflow box to bring the water line up to the rim. Is there any silicon I can use that drugs very quick? Or any type of silicone accelerator so I can take the old one off and glue the new one in?
Any tips would be awesome.

 

[Cory]

No silicone drys quick. You must let all silicone dry a minumum of 24 hours before using it for structural purposes or it can separate.

Also some silicones release ammonia while curing. Others release acetic acid sort of.