Quote Originally Posted by Help_Needed
Dude, you're still not getting it. In a DWC system, the oxygen is IN THE WATER. The water carries the oxygen to the plants. That's why you use the air stones, to create a high level of dissolved oxygen IN the water. Root contact with the air is completely unnecessary in a DWC environment. The entire root system of the plant can be completely submerged throughout the entire grow with no ill effects as long as you're pumping enough air into your reservoir.
NO, you don't get it. I'm not arguing that oxygen is carried thru the water in a DWC system. I've run DWC for several years. I am saying the plant will suffer when placed in a 5" square when first placed in a DWC system. By that I mean a young plant with little or no roots coming out of the bottom, and then being partially immersed in the water. The water (or nutes) will be sucked up by the cube, not enough of the oxygen. I have done experiments of taking two plants put in DWC. The first in a 6" pot with all rockwool, and the second one just filled with clay pellets only. They were grown side by side. The one with the rockwool did not do very well at all. The one in hydroton thrived. I had 4" net pots on a flood and drain system using hydroton as a media, and discovered the plants that were rooted in rockwool did not do as well as those that had no rockwool because they were rooted in an aero cloner. This was simply because the water schedule was once every 4 hours which was too much for those that had an inch of rockwool around them. A small cube would probably be ok in a DWC, although it is NOT helping the plant any in its younger days. After a while I've found the roots just develop above the cube and then thrive.
The placement of a plant into flowering is pretty stressful the first few days. That's why we keep the light further away the first day or two. If you want to give your plant a good start, don't put a small plant in a 5" cube in a DWC and expect it to thrive.