Using a hydrocorn or granit I usualy have plants about 5-6 feet tall. With 4.5 gallon, bucket system with a "T" for the water. I have only had a few problems with roots running down the feeder lines. Root bound has never been a problem. Thats with white widow on a 63 day bloom time. Always using a air stone to o2 the water and changing the water at 3 week intervals , with a ppm of 1400 and ph of 5.2-5.4, co2 injection of 1500 ppm. As with any growing the GWM is .468. Please note that GWM is a growers baseline for producton.