Hydrogen peroxide or h2o2. My bubbles splash enuff to keep the cuts wet so I don't submerge them. But I use plugs mostly. Less moving parts. I give them a squirt every few days and 9 to12 days later, roots.
Over all they look pretty good. Ph fluctuation can cause a lot of issues. Dwc is not my thing but my res always shifts up in ph and I use tap water. I always include my tap ec. Sorry I'm not more help. Good luck.