This Morning's Whole Wheat Levain

I made this using the Whole Wheat Levain formula in "Bread". It's 50% whole wheat with a rye sourdough starter (the book calls for a liquid levain, but I used my regular stiff starter). I used 1/10 of the metric formula in the book with a little more water; the finished loaf came out at 1.7kg. https://photos.app.goo.gl/xFQ8KYmDf5AEGYRAA 

I followed the DDT (desired dough temps) in the book: 70 F for ripening the whole wheat poolish, 76 F for bulk fermentation and 45 minutes of proofing, and then around 16 hrs in the fridge for an early morning bake with super off-peak electricity rates.  The lower temps should favor yeast and acetic acid in the starter; I think it worked for the acetic acid and possibly the yeast; the volume after fermentation and proofing wasn't bad.   

 I had been using a dutch oven for steam with convection (formula temps adjusted 25 F down), but I made one more attempt at baking on a stone (I'd like to be able to bake two loaves at once, with the holidays coming up).  I used a cast iron pan on the bottom oven rack; ice cubes before loading the bread to moisten the oven per Hamelman, and then boiling water in the pan after loading.  I also had a stone on an upper rack and did not use convection, hoping that the steam would not vent as quickly.  I got a little oven spring, not much.  But the crumb is a bit open.  Next time, I'll use the dutch oven without convection.and see how that works.