Day 8: The leafs of plant #4 got to big and to heavy for the thin stem, so I had to support her.
Day 9: Watered every plant with 0.5 l of fertilized water.
Day 10: Nothing to do.
Day 11: Also supported plant #2.
Day 12: Watered every plant with 0.5 l of fertilized water.
Day 13: changed the position of the fan a bit and took the support of plant #2 and plant #4 away. Watered plant #5 and #2 with 0.25 l PH-corrected tap water. Soil of these two plants got too dry because of a wrong fan position.
Day 14: Nothing to do.