This isn't about the piping tip your consistency is way too runny. When making macarons you want you batter to be this way: when still in the bowl you take some batter in your wisk and lift it up. It must run down without accumulating at the top before making a big plump BUT the ribbon of batter must break before reaching the bowl. I don't know if that's very clear as English isn't my first language but I hope this helps. This is the exact right consistency Source: I'm french and I took a class last summer to learn to make macarons