Help with converting recipes to use my starter

Help with converting recipes to use my starter

I’ve finally purchased Reinhart’s BBA book and would like to adapt the recipes to use my own starter. I’ve been using a firm starter (50% hydration) for years and have been turning out some wonderful breads. I fall solidly in the weekend warrior category, but take baking seriously. 

 

I’m looking at the BBA recipe for ciabatta, biga version in which the biga percentage is 178%. Most recipes I’ve used employ about 30-40% of my dry starter, so I’m guessing that I can’t just substitute with my starter using the same percentage? Or can I? 

 

Thanks in advance for any advice!

Source: Fresh Loaf