what are you temps in there, I don't see much air flow? I cant really tell in the pic. do you have a pic of the root ball in your DWC?
DWC is one of those things, I myself have never been very successful with; nor a fan of all the work/monitoring. DWC is all about keeping your enviro prefect.
the pictures you posted, IMHO looks like a snowball of problems, that no single remedy or action is going to fix.
since you're spending money, I did not see a temp/humidity monitor in there. some of the best money you can spend is on environmental gear.
IMHO: scrap the grow and start over.