There is differences with running both no question and I am not shitting on coir in way,but i'm not sure your accurate in all situations, from all the rooms I seen and studied the ratio is about 5-1 5 plants in 3g coir to 1 in hydro, thats mine yours maybe 1-1 2-1 4-1 etc i don't know, so if someone is growing 20 to my 4 I can assure you i'm not wasting any more water, I have no run off and if I pay attention to what i'm doing I can have my res low and hardly dump any for my water change, in the end I think there both about the same. nutrients is not a factor I mix my own I can do a whole run for pennies, but either way my nutrients get eaten I don't have 10-15-20% in run off. with coir you guys flush with nutrients in hydro I don't. There should be no big ph swings, if water harness, nutrients, res size, temperatures environment etc are all in concert I probably don't ph for my week, remember I want my ph to swing up a little through the week. I don't need to do much at all for top offs. by the end of the day 6 ( in any week) I want my water lower and nutrient levels low as well, for day 7 I want my plants to use its stored nutrients and get a drink of water before I hit it with fresh water and nutrients the next day. I bet most coir guys spend more time checking ph and ppm run off then I check stuff in hydro, I know I do. I bet I burn my lights less time to. But I also seen the opposite where coir guys out preform hydro guys, but its always the experience of one grower vs the other