Are my roots in bad form?

Looks like it. But nutrients can stain roots as well. The only way to know is to wash your hands with an anti bacterial soap. Make sure they are clean. Then feel the roots. If they are slimy then its root rot. To treat this, Remove any large patches of smiley roots, Get hydrogen peroxide 3% concentration can easily be found.Use just water with a ph at the same level you have been keeping it at( 5.5-6.5 range. I like to stick at 5.8) Add 5ml of the 3% concentration per L of water. So an 18L( 5 Gallon ) bucket would need 90ml ( 1/3 cup ) and let the roots bubble in this for about 1h. While they do that , clean your buckets air stone and hoses to kill the bacteria. Then put the roots out and rinse( or dunk) in clean water before putting back into the regular bucket. Do your current nutrient setup but add 0.5ml per L hydrogen peroxide 3%. Check the roots the next day. Some will be healed, Cut and remove any remaining slimy ones. From what I can see canna aqua is a salt based nutrient and not living so you should be fine adding hydrogen peroxide. Its completely safe for the plant Its water with an extra oxygen molecule. Keep adding 0.5ml per L every day for a week(no need to change water, Just add more as it changes to water by loosing the extra O molecule.

most root rot DWC is caused by high temperatures or not enough air this does look like root rot to me is the plant suffering does it have droop or anything like that???