Starting a sourdough culture on Gold Medal wholewheat flour

The description and pictures below present an attempt of starting a sourdough culture on Goldmedal stoneground wholewheat flour. On all days the environmental temperature was around 30 C.

DayDescription
1 50 gram wholewheat flour and about 50 gram of (bottled) water are mixed. The thick paste is put in an airtight container and closed.
Photos 1, 2.

2 The sourdough culture has expanded substantially. Relatively large bubbles are visible.
Photos 1, 2, 3, 4.

25 gram of the sourdough culture is mixed with 50 gram bottled) water and 100 gram of bread flour. The cup is covered with cling film. After about 6 hours the culture is more than doubled in volume and does not expand further.
Photo 5.

25 gram of the sourdough culture is mixed with 50 gram bottled) water and 100 gram of bread flour. The cup is covered with cling film.

3 After about 6 hours the culture has increased in volume and does not expand further.
Photo 1.

25 gram of the sourdough culture is mixed with 50 gram bottled) water and 100 gram of bread flour. The cup is covered with cling film. After about 8 hours the culture shows no sign of life.
Photo 2.

It appears that the wholewheat flour ferments fast since within a day it already doubles in volume. However, it can not ferment the bread flour.

After 1st feed After 2nd feed After 3rd feed