you can over water in coco, if you have a small plant in a big pot that hasn't rooted the pot out properly , it can take days for it to dry out especially when you water till you get run off, i have grown 6oz plants in 11ltr pots and they took 2.5ltrs of water every day, if you let the plant root the pot out each time you pot up you can not over water in coco, no matter how much or how often you water