Most growers are not aware that a plants root system is as long as the plant is tall. Soil SOGers can compensate with large footprint containers that don't need to be too deep: a concrete mixing tub from Lowes/HD should do the trick. However, if you try to use something low like this in a DWC system, you will run into a ton of root born problems around the 3-4 week of flower, that are blamed on nutrient deficiencies, when that is seldom the cause. Why?
DWC roots function optimally when they occupy the same relative space as they would if the roots were growing down, unrestricted in soil searching for moisture and nutrients. The farther away from this a home growers system is, the more problems are likely to result. I have yet to see a DWC system that attempts to duplicate a plant roots natural tendencies. Growers who get good results with DWC would get much better results with significantly less potential for sickly plants, and nutrient deficiencies if they switched to High Pressure Aeroponics (HPA.)
A strain that grows 3 ft above ground will grow a 3 foot deep tap root during the grow phase. A few weeks into flower a large root ball develops near the plant in preparation to drink as much P & K as is available in order to develop nice fat buds. Under ideal conditions the root ball resembles pompoms. On a 3 ft tree this pompom could be the size of a basketball. Since the roots don't know when to say when, they will feast until they poison themselves. SO BE CAREFUL with the P & K. There is such as thing as too much, although some strains can eat more than others without consequences.
Let's compare the two systems
A typical DWC root zone chamber is shallow. It contains a low pressure pump, spray bars, bubblers, and nutrients. All is fine until 3-4 weeks into flower when those pompoms start clogging everything up into a tangled mess- literally. Why? The inevitable massive root structure has no where to go. So is DWC SOG off the table? Hell no! It's alive, and better than ever.
SOG & HPA are a match made in heaven. Inside the root zone of a HPA grow pod, all that's needed are the mist heads, leaving plenty of room for the crazy root growth to quickly come. A HP pump (costs <$150) and rez (with bubblers) sits outside the root zone. It pulls nutrients out of the rez and pushes them through small 10-50 micron mist heads under 50-100 psi, which delivers them to the roots as an aerosol, which is ideal for the roots to feed upon. What the roots don't consume falls to the bottom and are eliminated via D2W.
To accommodate a genetic 3 ft plant, that has multiple 1 ft colas above the screen you will need about 6 vertical feet and then your light. Lowryder type strains reduce the vertical height some 12-18".
Aside from maintaining pH (5.4-6.0), nute strength (600-800 ppms in full bloom) and making sure the RH inside the chamber is ~70 degrees, and usin chelated nutrients, silica, and fulvic acid you can pretty much it back and watch the real fun begin
