Fermentation Issues With Personalized Recipe (Foam in airlock)

Hey all,

Long time lurker, first time poster. I love all the advice on this website.

I've been brewing for about a year now, almost exclusively helping friends. Just recently my brew partner moved out of state, and so I have taken the reigns and got myself a kit.

I am currently on my third batch and I am running into an irregularity that I am not familiar with. I made a 6 gallon batch (admittedly in a 5 gallon fermenter) and foam is seeping into my air lock. I've made larger batches in 5 gallon primary with my friend before and had no issue. Any advice on how to handle this? I tried making a back up blow off with tubing on an airlock but I was unsuccessfull in fitting the tubing onto the airlock. Does anyone know of any videos out there that can help me do this? I have a larger carboy, can I swap to secondary prematurely (i.e. 3 days instead of 5-7)?

Here is the brew recipe. I was hoping it would turn out as a porter:

.5 Crystal Malt
.5 Honey Malt
.5 Chocolate Scottish Malt
.5 Brown Malt Fawcett
.5 Caramel Munich

2.5 Light DME
3 Dark DME

3 Oz of Kent Goldings Hops

WLP023 Burton Ale Liquid Yeast

Pull the airlock out of the bung, put the tubing directly in the bung, (don't push it in far, or else it'll siphon out beer! Just below the surface of the lid/carboy). Voila, blow off tube!

Don't transfer it yet....it's happy, just give it a place for the krausen to go and you'll be fine.