I just racked off my pumpking ale due to a lot of trub there is only about 4.5 gallons in a 6.5 gallon carboy will this be a problem of should I top it off. I don't want to dilute it or anything but will that extra air cause a problem.
Primary 1: Imperial Stout
Primary 2: Golden Ale
Keg 1: Nothing
Keg 2: Nothing
The ideal situation would to purge the carboy with co2 before racking. Being we don't live in an ideal world, you are fine. If you add water, it will also contain oxygen so it is a matter of picking your poison.
I just bottled my pumpkin ale which when transferred to the bottling bucket proved to have 4.5GAL in it. I'd rater less brew than watered down stuff. There's enough of that in coolers across the country. I'd go with what you've got.
--Ramone, I am the poster formerly known as gaelone. Tell 'em, Fred.