So: rez temps are too high. I would strongly suggest investing in a chiller. They are not cheap but they are definitely a game changer.
TDS at 595 is a bit high but not enough to worry about yet.
I would discontinue the CO2 as it’s simply a waste of space and money. (To take advantage of CO2 you have to be in a closed loop system with a high partial pressure of gas, along with high intensity lighting) Essentially all of your parameters have to be perfect to take advantage of it and if your lighting is insufficient you won’t benefit from it.
That one root showing is going to be joined by many many more. The plant has found your rez so it will start pushing more roots. When it does your canopy will likely stop growing while it works to build a root ball. When it’s done it will be about the size of a basketball.
Here’s my journal; I would go to the end and scroll back up, but I’m doing a single DWC in a 2 X 4 X 5 SCROG with a target of 16 oz of flower.