You've had some effed up luck on these plant bubonic. i've never seen anything like it (that's not really saying much).
I've been growing in DWC for a little over a year. Started with Emily's Garden and a 150 watt... i've moved up a bit since. I've had none of the problems you've had. I know that doesn't help you. But when I look through what you've done and just knowing what I've done (and believe me, i've screwed up plenty), it seems like the additives and gizmos, tubing and wires are just in your way right now (figuratively).
You seem like a pretty intelligent person and you've done your homework. My advice is keep it simple. Super simple. In fact, oversimplify! I over-thought things at first, too. PH, EC, TDS, RO, DWC, LST... you get the picture. Info overload. I wish I had a few of the toys you have, yet I've managed to keep myself happily medicated and the wife mostly appeased (she really hates that I grow). I started with brita-filtered tap water, lucas, superthrive and bud candy. that was it. didn't do too bad. Switched to RO and AN (i only use a few of their products that i can afford), love it! The only thing electrical in my space is the light, the fans, and a dual-outlet air pump. Simple.
The point of keeping things simple is you have way less to troubleshoot when things go wrong. Start with a good foundation with only the basics. Then start employing your badass pumps and kickass teas and whatnot. Don't get rid of them, just get them out of your way (for now) so you can grow!
AN's Sensi is 2-part like lucas but their stuff is PH buffered and it works amazingly - perfect for RO. I really only need a PH meter if things start to go sideways but they haven't. When they do,I can call AN and they'll help out.
I hope this helps you and you don't get discouraged. I apologize for the lengthy post in your thread and wish nothing but the best.
-hg