branches dying!?

Hello all,
So,I have these 2 uncontrollable DP orange bud in NFT 22 days into flower,packing out my grow space and now the lower scratty branches are yellowing then goin brown then dying or I am removing them.Problem is,I cant get in the space to check the roots properly, last time i checked,the roots where only just goin over the edge of the tray drain,so I tucked them under back on themselves and that seemed to work(cant get in to check now)I am doing everything by the book,my temps-mid 70`s,humidity45/50%,p.h-5.8,nutes-1120,give or take,big fan,exhaust fan are all fine.I am also adding h2o2 every three days to add extra oxygen and as a preventative of root rot.From what roots I can see they all look white and lots of.This seems to be something else? Will adding a dose of silicon+ aid combat against disease? Oh and I forgot,theres a few of the dreaded rust spots on a couple of upper leaves.Will post pics later,all help appreciated,Thanks,RM.

Yes pics.....do you think they may be rootbound in some way? My plants will get like that when they really start getting big.....rootbound that is....not branches dying.
Pics would help alot.....sounds like you have your system dialed in pretty well.

You got adequate calcium in the water? What's your water source, tap or RO, and what exactly are you running for nutes?

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Originally Posted by Weedhound

Yes pics.....do you think they may be rootbound in some way? My plants will get like that when they really start getting big.....rootbound that is....not branches dying.
Pics would help alot.....sounds like you have your system dialed in pretty well.

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Here`s the pics,Its not lookin to good if they keep dying back at this rate![attachment=o171462]

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I am using tap water which has been stood for 24hrs,originaly at 6.9 taken down to 5.8 and its base is 240ppm.I dont know how to test calcium levels?.Hi weedhound,I dont really know what to say about the root bound question...they are in 4" rockwool cubes and have full roam of the 3footx2foot tray,but there is lots and lots of roots in there so it could be a possibility,the plants are about 6foot tall,that said,theres not much I can do about it now as i wouldnt be able to move them without cropping and thats not an option yet.:(

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This is serious,like I said..if this keeps up then im not going to get an harvest at this rate.One thing I forgot to mention was that when I remove the dead/dying branches the insides look normal and healthy(white and foamy)compared to an outdoor plant that went rotten back in the early autumn,which was brown inside the stems.This is a good sign,yes?. Anyone willing to guess what the yellow spots are on the top most leaves? ALL HELP MUCH APPRECIATED. RM.

Huh, that actually looks like drying from a combination of fan blowing right on a part of the plant, low humidity, and possibly the plant being too limited on root space to replace the water lost through transpiration.
6 feet is QUITE large indoors! What's up with that? In soil, that would require at least a 10 gallon pot to survive... in hydro, I'm not sure, but you're really pushing the limits for plant size indoors.

So what should I do then,Im scared to chop of the damaged branches incase it continues straight to the tops? Will thinning help and could it be too much for a plant 25 days into flower? My humidity is higher than I 1st thought,its actually 77% is this too high?It fluctuates up and down depending on how much water I spill during a res change lol. I need the fan that close Stinky as my plant tops are real close to the light and the fan is cooling the tops down.. At a lost end.RM.