Ok so forgive me if I'm so off base about your setup but...is that aeroponics? Or dwc? Or both? The previous post about water temps is accurate...but those water levels look really low to me. The net pot should be skimming the surface of the water and the more bubbles the better. Roots almost look dry? They do like to dry out in soil temporarily...but remember they are responsible for nutrient uptake and water. About 80% of the root mass should be in the spray ( for aero) or submerged in rich oxygen water created by a good pump and at minimum. One 6 inch airstone for that tub. A tub that size....go with two for really good results.
In hydro letting roots dry out isn't a real concern because in hyper oxygenated water they get plenty of oxygen. That's really the key for hydro growth>soil growth. Tooons of oxygen. The very reason scientists say all life was so big in prehistoric time ....more O2 in the air allowed for more absorption.
Your on the right path but do yourself a favor and watch hygrohybrids channel on YouTube...he's a hydro pro and has awesome video explaining the science behind it.
Your almost there my dude...just a few tweaks!