Can't figure out what's slowly killing leaves one by one. Pictures. Help!! :)

Hi all --

Legal medical grower from Maine, I run an indoor custom built 24 bucket RWDC, I pulled a plant out of the system the other day after I noticed it's leaves were browning and curling/crisping up on the edges one by one, probably about 2 a day for several days. Can't figure out if this is a nutrient lockout or a root rot issue. I pulled the plant about 4 days ago, now I'm noticing another plant showing the same signs.

Anybody have an idea what this may be from the pictures attached? Ask any and all questions I'll have answers waiting.

Thanks all

The first/second picture really best depicts what it looks like

Bump...

If this helps any, the back of the leaves also lose their green color and look indented where the brown markings are, as if the affected areas have been scraped off

manganese or potassium is off maybe? What do you keep your systems pH at?

If you are assuming root rot it is very very easy to tell, its a smell you never forget. Like someone has been egg farting in your tent. I find if you flush your system and adjust your air your plants will still bounce back, but the stress still greatly effects the end result.

I would say if it only 2 plants in a 24 bucket system just pull the 2 and quarantaine, they look to still be in veg, if it is nutes or the roots you can monitor them but if its something more serious I would like to protect the rest of the operation.

The first few pics look like a bug problem I had once. It could be thrips. They tend to live on the underside of the leaf and can be pretty tiny. The silvery shine on the leaf is a sign of thrips.

i dunno, that sort of looks like a nute problem, but it sort of looks like thrips...the damage looks like calcium deficiency, but cal damage is random, it will go across veins randomly. your damage seems to be strictly between the veins, which makes me think it might be something eating them. those shiney spots are odd, too. is that part of the damage or did you spray something on them?
i think i would try a good spray, something with spinosad like http://www.amazon.com/Bonide-252-Captain-Jacks-Concentrate/dp/B001VJBYMC/ref=sr_1_2?s=lawn-garden&ie=UTF8&qid=1463116657&sr=1-2&keywords=spinosad+insecticide
this is good shit, organic, effective, half the price of monterey.

Doesnt look like the thrips ive had issues with. Looks like over feeding to me.

like i said, it kind of looks like both, but after thinking about it overnight i'd say check your nutes and ph as well. that looks like classic calcium deficiency.
http://www.growweedeasy.com/calcium-deficiency-cannabis

make sure your ph is good, anything below 6.2 contributes to cal def. i don't do hydro but i understand thats quite high for hydro. i use coco, add pellitized lime to it when i'm mixing it up, and use a spray called ferti-lome yield booster. its a cal spray for tomato bud spotting, i like it because it doesn't shove extra mag down your throat wether you want it or not like cal-mag. you could use it and not worry about your ph being too low to absorb cal
i'm still curious about the shiney sticky looking spots....overspray from something or symptom?

What is that sticky/ wet spotty shit all over those leaves? Looks like you sprayed something and it burned?

As said above first pics look like Thrips. You can treat that with garlic and soapy water I think.(or was it that the treatment smelled of garlic?) Ah yeah its an oil that I cant remember the name of, sorry. Bloody stinks though and its a pain in the arse. Does look like a deficiency in the last pic with that crispy curl to the leaf. That could be as simple as your PH been off which is always the first thing to check when deficiencies happen.
Hope you get it sorted. If it is thrips you can get rid of it over a few weeks.. Just googled, Its Neem oil that you can use.
If that is the problem you need to find the cause, Do you have a messy garden, waste laying around or any rotten material?
Anyway Good luck resolving your multi issues.
C.W

The plants are healthy and vigorous , the slow browning and dying of old fan leaves is nothing to be worried about.

looks like potassium to me, usually when your edges get a purple tint to it is a strong indicator calibrate your ph meter and double check, would be much more helpful if you posted nutrient levels and your conditions