What the freakkkiin h#ll is wrong with my plants?

[TheGardener_]

I have 2 nypd and raspberry coughs in a gt205 nft system

I am using 3 part ghe flora series (grow micro bloom) in 10 litres of water, mixture;
15ml bloom
10ml micro
5ml grow
With ph of 5.8 to 6.2, I try to maintain 1.6ec but hit 1.7 to 1.8ec, I have it on feed of 15 mins every 2 hours but the leaves on the raspberry coughs closest to the edge of the nft system where the water funnels out, are burning and dropping off on the 1/3 lower branches, what am I doing wrong? Should I be using diff nutrients? I maintain room temp of 26-28c and humidity 50-60 as it is in 2nd week of flowering, lights are on 12/12 with a 250watt hps.

Are my nutrient mixes okay? Room humidity? Lighting is a foot and a half away as the plants are getting tall and no space!

PLEASE SOMEONE HELP I AM A UK GROWER (1ST GROW) pics below

 

[Tobor the 8th Man]

Can they get potbound in that set-up? Does it start with the lowest leaves?

 

[TheGardener_]

I don't know what potbound means? Yes lowest third of the plant

 

[Tobor the 8th Man]

Can the roots become tightly packed in the space they are in. When that happens they can drop the lower leaves.

 

[HydroRocks]

Need better pics, like of the entire plant. From those pics can not really tell anything.

I would double check your meters as something could be off.

 

[TheGardener_]

Well it is an nft on a tray, so it lies on a bed of its own roots. I think I might have to buffer my ec and ph meters

 

[TheGardener_]

Adding pics now

 

[Tobor the 8th Man]

They have plenty of root space so root-bound is not it. I didn't know if the tray was open like you pictured or they were in there own square of space and could get jammed in there.

So now you just go through the check list of plant trouble shooting.

Check ph
Check ppm/ec
Check solution temp
Check it during the flood to see if all the roots are getting solution
Check it after the drain to see if all of them drained the same
Check root zone temps right before the flood and during the flood
Check for pests

You should do some of the above to a plant with no symptoms and also a plant with symptoms. To check that somehow the bad ones are not getting a different ec, ph or temp by the time they get the solution. Or if they don't stay flooded as long or stay flooded longer.

It could be that nothing is wrong. Plants lose leaves. Sometimes inside well cared for plants keep every leaf nice and green until they just get so old they are spent and the newer leaves are out working them so they are a waste to have. Your upper leaves look nice and healthy so this might just be as simple as old leaves and nothing is wrong.

 

[TheGardener_]

Cheers buddy! Checked everything already yday and today! Iv been advised to keep drain on 247? I had it 15 mins on every 2 hours