I never grew in coco and a rockwool cube may be your answer, but from my experience rockwool cubes can be oversaturated with water as well so you kind of have to get the saturation part down. I go with the rapid rooters because they dry a bit more evenly and hardly if ever become over saturated...
I would put the water temp at 68 degrees and get the PH to 5.8. That would create the most dissolved oxygen in water while putting your PH at optimal levels for nutrient uptake for hydro. Increase your C02 to 1200-1500ppm lights on. All this will be for nothing if you cant raise your room temps...
I think your set up will have several counterproductive issues as many have already stated. While using the LED's you want your rooms ambient temps to be between 80-85 degrees Fahrenheit. While running CO2 you could definitely get away with 85-90 degrees Fahrenheit. Unfortunately, it looks like...