Honestly it doesn't look like any nute burn I've ever seen. Looks more like pH burn, but so extreme I've not encountered it personally. And is it the whole plant doing that or just the top? OP what is your pH? May be some fungal issue none of us have seen because you're in the southern hemisphere.
I've had this happen before. Boys at the bottom, girls on the top. Pinch those nuts off and keep going. Monitor nodes in case more boy cooties show up. You can still have a sensi harvest.
Pick up a "duct defender" screen to go over your air intake in case bugs are getting in that way.
You really need to pick up an electronic pH meter. I can tell you've spent good money on your set up, so don't skimp on a tool that is a MUST for hydro. If your pH is too high or low, nutrients...
Maybe, but the kind of bug who will eat and leave, like a termite. When was the last time your space was treated for termites, OP?
The damage also resembles pH damage. Be mindful if it spreads or reappears, but your grow looks totally healthy otherwise.
What caused the mold and where was...
Lose the makeshift humidity dome, you need that for clones NOT seedlings. Read this, it's the best thing I've found for troubleshooting seed concerns... http://www.mandalaseeds.com/Guides/Germination-Guide
GH nutes build up salt and lock up so bad it's ridiculous. Just real easy to overdo them. When was the last time you dumped the reservoir and cleaned it? Take a little CLR to that airstone and components.
Let your plants spend a few minutes in plain ph down'd water to detox a little bit...
A good flushing (one gallon of water per gallons in your container) will leave your plants *drenched*. You may need to set your container over a five gallon bucket while you flush to avoid overflow. Adding nutes tomorrow will add insult to injury. Water with nutes when the flushed soil dries...
Lose the distilled water and use tap water. Otherwise you're missing out on calcium and other minerals that naturally occur in regular old water.
Flush every four weeks. Remember to adjust ph AFTER adding nutes.
Your plant is still healthy enough to bud, but crystal production might be on...
According to the Jorge Cervantes grow bible, chlorine deficiency AND abundance look the same. Are you on city water? When you fill up our reservoir stick your head in, does it smell like a public pool? Maybe look into getting a smallboy filtration system to get that excess chlorine outta...