French Bread with poolish

After making the buttermilk bread I made a simple French bread using the poolish. To make the poolish easier to make I use a recipe calculator to calculate the amount of poolish, water, flour, yeast and salt for the specific hydration and weight of the loaf. It seems to work OK. I got a big hole in the center of the loaf. This comes from wrapping a bubble of air into the loaf when forming it. Sorry, I will be more careful next time. The recipe is standard French bread from any book. So is the method. The only difference is the use of the 50/50 poolish living in my refrigerator. Here is what it looked like.