Increasing Volume with stone ground flour

Hi everybody, hope you can help...

I need Advice on increaaing loaf volume when making sourdough with stone ground flour.

I made the decision months ago to start making all my sourdough with a local very high quality organic stone ground wheat flour (12.8% protein) for flavour, nutritional & economical benefits. However after 3 months of testing formulas and methods I feel I have finally got the best results I can (given my few years experience & the nature of stone ground flour).

My question is... can anyone give me advice into increasing loaf volume and getting a more open crumb similiar to the results of roller milled flour.

I understand why stone ground does not behave the same as roller milled and I definitely think the flavour and pride in using traditionally local milled flour is superior but I do miss the volume and texture of roller milled some what.

Thanks alot

J