Added some protective foil to reduce evaporation. Also added an airstone to keep the water from being stagnant. Also upped the amount of water to 15 liter. It took 6 days for the plants to drink up. At the end of day 7 the soil is dry again. So its enough for my buddy to top dress and fill the Reservoir once a week in my absence.
Now im back to handwatering until my vacation starts.