I was just sitting here thinking that you could weigh your cup/soil/ combo before you water. Then you know exactly how much water is contained in the cup. Obviously the plant will grow and start to weigh more, but compared to the dense water it probably would affect calculations too much. Does this seem like a good method? Or is this too scientific...
Over complicating things man, stick a finger to the second knuckle. If its moist- don't water. Otherwise add some water.
But I'm an engineer! I get off on precision haha. Definitely keeping a very well manicured logbook. I want to set up a camera inside the growbox and have it take pics every 30 mins and link that to auto measurements of the essentials (ph, tds, humidity, water retention etc.). Dude you could just drop that into excel and be ready to analyze haha.
if that is the sort of shit that gets your jollys off you could also measure the rate at which the plant absorbs the nutrients and the evaporation rate. i would imagine you would have to weight the plant/soil/container completely dry, your water/nute mix and go from there?
it could also provide critical information on the difference on the different stages of growth. who would have thought a bunch of pot heads doing a bunch of scientific shit w/ cannabis?
it technically wouldnt be automatic. you would need to weight the base medium and container. water weights between 8.3-8.5lbs/gallon depending on the minerals and what not in the water. you would weigh the container every couple of days to analyze the amount of water usage by the plant. this way you could give the plant the exact amount of water it needs without leaving excess in the medium which we all know can cause a ton of problems..