When it gets right down to it, the larger container candles need more candle wick. This is necessary to provide the appropriate amount of heat required to create a melt pool that fully covers the candle surface. If you do not have the correct wick sizes, or quantites, tunneling will occur because the full surface of the wax is not consumed as the wax is burned.
So on that note, I made this double wicked scented soy candle using a tangerine fragrance, and turned it into a video. Because wick placement correct wick placement is so important, I showed you one of the ways that I use the wicks in combination with a dowel rod, and a glue gun to secure the candle wicks exactly where I want them before I pour the soy candle wax.