Dont be watering every day , If your wanting to water your plants on same days then just leave all plants unwatered until the last one has dried out , i would of thought would only be a day or two between drying out time . Then just have watering cans sitting in grow room and when you come to water use a 1 ltr bottle as a measure , that way you know how much each plant is getting . My plants get watered every 3-4 days ith 2 ltrs . If you water every day you ill cause root rot as you have to let soil dry out ,