Dry crispy leaves with brown spots: What should I do?

[NamTran]

Strain - RQS Cheese Auto
# of Plants - 4
Grow Type - Hydro
Grow Stage - Seedling- day 13
Setup - Low Pressure Aeroponic
Light - 4x 50W COBs, currently running at 2
Nutrients - Canna Aqua
Medium - Grodan Rockwool
PPM - 630 (PPM 500) or 1.2
PH - 5.9
RH - 50% to 65%
Room Temperature -75 to 83
Solution Temperature -71 to 74
Room Square Footage - 10
Pests - None Known

I grow 4 plants on one nutrient tank but only this one became like this. I tried looking into the Problem thread and it seems to be nutrient lockout. But I'm not sure about that. Any idea what might it be and how should I fix it?
.

 

[Old Salt]

to the forum...

The plants look like they aren't getting enough water. Water the top of the medium several times per day, or install drippers until they develop a robust root system outside of your pots.

 

[Growingasmile]

Strain - RQS Cheese Auto
# of Plants - 4
Grow Type - Hydro
Grow Stage - Seedling- day 13
Setup - Low Pressure Aeroponic
Light - 4x 50W COBs, currently running at 2
Nutrients - Canna Aqua
Medium - Grodan Rockwool
PPM - 630 (PPM 500) or 1.2
PH - 5.9
RH - 50% to 65%
Room Temperature -75 to 83
Solution Temperature -71 to 74
Room Square Footage - 10
Pests - None Known

I grow 4 plants on one nutrient tank but only this one became like this. I tried looking into the Problem thread and it seems to be nutrient lockout. But I'm not sure about that. Any idea what might it be and how should I fix it?
.

Could be a disease, or a sensitive strain that needs a ph closer to 7.0 they look a bit oxygen deprived to me are their roots constantly submerged? if so do you have an air pump? are you giving it full strength nutes?

 

[TorturedSoul]

The plants look like they aren't getting enough water.

Which, in a hydroponic environment (and, I assume, in an aeroponic one), could equate to "there's not enough dissolved oxygen in the water that the roots are getting."

Check to make sure that the individual emitter(s)/fogger(s) that supply that specific plant are functioning properly. I'm guessing that they might be easier to partially - or even completely - clog than a run of the mill hydroponic drip-feed emitter.

Do you have any way to check the temperature of the mist/fog that is hitting your plants' roots (and that plant, specifically)? Unless those plants are all clones from the same mother, they could have differing tolerances to such things. And it could be possible that your pump, in having to force moisture through tiny fogger/mister orifices, is heating the solution up (especially so if one or more of those orifices are partially or wholly obstructed).

There have been a few aeroponic grow journals here over the years. Most of them did not end well, IIRC. The method appears to be somewhat less idiot-proof (so to speak) in general than hydropoincs.

Also, if you have not already done so, I suggest you take a look at this thread (and bookmark it, in case it might come in handy later) :
Cannabis Plant and Pest Problem Solver - Pictorial

 

[NamTran]

I do run an air pump into the reservoir, plus it is a bato bucket so there is always some water left in case the pump fails. (Roots are touching the water ). Temperature is a bit high at 75 f because of the pump so I guess it could be a reason. I'm redesigning a high-pressure system with a pressure accumulator so it could solve this problem of temperature. But still I don't know why it's only one plant (

 

[Growingasmile]

I do run an air pump into the reservoir, plus it is a bato bucket so there is always some water left in case the pump fails. (Roots are touching the water ). Temperature is a bit high at 75 f because of the pump so I guess it could be a reason. I'm redesigning a high-pressure system with a pressure accumulator so it could solve this problem of temperature. But still I don't know why it's only one plant (

Gotta get those reservoir temps lower 70f is max any above that and dissolved oxygen reduces dramatically plus if you think about it the roots in nature reach down 2-3 feet at least and 1ft under the ground you start reach around a 60-65f temp consistently

 

[NamTran]

Time to buy some reflective duct-tape I believe (