My plant is twisting itself..

The amount the internode will stretch depends on a couple factors. Ofc we have baseline genetics, then you have turgor pressure which is responsible for cell elongation, higher the Raye of transpirstion the higher the pressure, the more the cells will be able to elongate. This is kinda coupled with light intensity, as generally speaking the higher the intensity of light the shorter the internodal spacing. Plant is getting alot done In one cycle, just kinda happens to be stretchy. Purple stem is not a problem unless it stays purple, then your looking at very slight phosphorous delay. Normally just means medium could do with lil more oxygen though I find. Stem is lanky but she looks strong and well reinforced. I'd just keep on keeping on! If you know your temps to be high and humidity low try balance that out a little. If your transpirstion is high make sure thay pot has water at all times.