i grew some plants a while back w/ an idea i was pondering. they did freaking awesome. havnt done much research to see if this is the reason they did so well but it sure didnt hurt them. the basic idea is using layers of dirt and lava rocks to provide the roots more air to grow through. the roots would grow down through the lava rocks and the lava rocks would suck the water and nutrients from the dirt through capilary action. the dirt would provide more continued release of water so waterings would be less frequent than regular hydro. i used twice a day to water. they dried out nicely between waterings. i didnt always feed as i thought the dirt would hold onto some of the nutrients so like once a day or every other day sometimes with a mild johnsons plant food mix. attached is a drawing of how i layerd the mix. i would like to know how this works out with flowering as i didnt have a chance to flower because my roommates were idiots. let me know what you think.
for more info on this or somewhat similar methods i found you can google "lava rock semi hydro" or just research "semi hydro" for some good ideas. i think this method is more semi-semi hydro.
in theory it makes perfect sense. i think i'll incorporate this idea into my next grow, which was gonna be semi-hydro anywho. instead of having layers of soil i'm just gonna use coco.