Please note -- I am a noob in my first year of fermenting. But, I have now made enough batches of either beer or mead to begin assembling my grimoire of practices.
I also use 1 gal carboys, and I use two tactics to reduce foam, with very good results.
1) I set up a blow off tube (use the base of a 3 piece airlock, attach 1/2 hose from it to a empty liter soda bottle with a star san solution in it. Sanitize the airlock and hose prior to hooking it up.) The large bore allows it to off gas easier.
2) Rock or stir the liquid often in the first several days. I try not to splash the must, but I rock the liquid back and forth a few times to help it off gas. With beer I prefer to rock, it exposes it to fewer pathogens than stirring. Rocking also ensures that there is a blanket of CO2 protecting the headspace of the must. But, I will also use a small plastic racking cane in my screwgun to stir the liquid if it seems like it's growing a lot of foam.
Also, from my beer brewing experiences, I am not keen on adding large solids to my 1 gal carboys, like chunks of fruit or raisins. Foaming has always been a bigger problem for me with chunks. In my two trials with fruit, they clog the blow off.
If you have really bad must foam or want to use solids in your must, you might want to do as PitBull mentions -- get a bigger carboy for that primary fermentation. (When I do my first melomels, I might invest in a 3 gal Better Bottle for exactly this.)
On those occasions where I knew that I'd be away for a couple of days (I sometimes travel on business) I put in a drop or two of FermCapS foam control, and it works pretty well. But I try to avoid using the stuff... it contains silicon compounds and who knows how good or bad it is for you.
