Help with plumbing for overflow and sump?

[brigoody]

Hello, I am a newbie starting a 90gallon saltwater FOWLR tank. My tank has a built in overflow in the rear left corner. I am using a 20 gallon sump. The questions I have are with the plumbing I should use. Is PVC or tubing better? I was leaning towards tubing since I am new at this and figure I'll make some mistakes that I'll want to correct.

I also have a large bulkhead (not sure where they are measured), but a 1" male adapter fits in the threads. This bulkhead is in the drilled in the bottom of my tank. Should I slip a coupling into the bottom of the bulkhead and then use tubing or should I buy larger tubing and put it over the threads? The pipe leading into my overflow is only 1".

I also purchased a ball valve for the return pipe, but how and where should I place this if I use tubing?

Another question that I feel stupid for asking, but does the gasket for the bulkheads go inside the tank or on the outside between the tank and the nut?

[Fireworks]

First off, the gasket goes on the inside of the tank. If you put it on the outside, water will leak around the threads of the fitting. Myself I like to use pvc pipe whenever possible because it is easy to work with and it looks much better then tubing. All you have to do is measure, cut and glue. Either pvc or tubing will work fine, just a matter of preferance.