I don't even use the cap, no need. It's probably better because you don't want the beer under any pressure, you want no co2 to remain in solution so I use very little water in my airlock and no cap especially in the secondary.
Secondary: DogFish 60 Clone
Up next: The Bestist Bitter
Bottled: Blackout IPA
"Ooo Pretzels and Bier!"-Heidi Klum