Does my return line need to be cemented?

[hebdizzle]

I have an innovative marine INT tank which has a 3/4” return line that runs through the bottom of the tank. I have the bulkhead installed — do I need to cement the 3/4” PVC that is between the bulkhead and the locline?

 

[KrisReef]

When the power goes off will it siphon your tank water into the sump?