Sourdough bread, with much holes, lightweight class

Made a similar bread before with yeast, http://www.thefreshloaf.com/node/40916/white-bread-light-weight-class

In this version it's only sourdough.The recipe is for 2 bread.

Instructions, 2 bread
day 1 sourdough: late evening before bedtime
*100 g sourdough starter, non active. I use this time 70 g for 1 bread
*200 g water, 40 degree celcius
*150 g wheat flour, high protein
*50 g rye flour

Mix all ingrediens in a bowl and cover it with plastic film and let it stand in room temperature (20-24 degree celcius) overnight until it has been very bubbly.

Day 2 morning
*sourdough from day 1
*450 g cold water
*750 g wheat flour, high protein
*20 g fine salt

1)Mix all ingredients, except the salt and knead the dough in the machine for 8 minutes, 5 minutes low, 3 minutes high speed. Add the salt and knead it 2 minutes more. When the dough is done it should have good elasticity and be little sticky

2) Grease a plastic box (not to big) with oil. The dough should rise in it at the height, not at the width. Let it proof in room temperature until the dough has double its volume which can take 3-5 hours, in my case 5 hours. Meanwhile fold the dough in the plastic boxs 3 times, after 60, 90, 120 minutes. Then let it proof the rest of the time in peace and quiet but my dough like symphonic metal bands so I dont know quiet is the right word. Fold the dough with wet cold hands by fold the dough from the left into the middle, from the right into the middle, from above to the middle and from below to the middle and turn the dough with the folded side down.

3)Put the oven on 275 degree celcius. Place one baking sheet/stone in the middle and one sheet at the lowest shelf in the oven.  

4)Take the dough out from the plastic box on a floured surface and fold it one time as the instructions above. Put the dough in the oven and some throw some cold water (maybe 100 g) on the lowest sheet in the oven to create steam. Lower the temperature to 250 degree celcius

5)after 15 minutes lowering the temperature to 200 degree celcius and ventilate the oven by open and close the hatch. repeat the ventilation every 5 minutes until the bread is done. Total time maybe 30-40 minutes, the inner temperature should be 96-98 degree celcius.

6)let it cold and enjoy with butter a good cheese or other good stuff.