Can it be N toxicity even though runoff ec is much lower than inflow?

[grou]

H-45-50%
T-20-22c
24/0
Linght distance-50-55 cm
Nutes-T.A. Coco dualpart; cal/mag (sometimes) and fulvic acid(sometimes)

These plants are autos, in 12 liter pots. COCO i feed them twice a day on 12 am and 8pm.
Inflow ec-1.8 outflow-1.2 on one plant and 1.4 on other. Light green clawed tips are present in new growth, which is N toxicity to my knowledge. 1.2 ec runoff plant is ironically healthiest plant in tent. 1.4 ec-second healthiest, but on this plant, lower leaves are drooping slightly( this plant is closest to the fan). About 5 days ago, runoff ec was 0.9 and thats when i started x2 daily feeds. Runoff ec gone up slightly, but new growth leavf tips started to show these symptoms. I have 2 more plants (one with same runoff as inflow and second with +200) which are nowhere near the size of low runoff plants. Should i lower inflow ec? Any suggestions? I also measured runoff ph-6-6.2. Can it be overwatering?

 

[grou]

These plants are about 1 month old

 

[Bukvičák]

If your inflow is 1,8 and your runoff is 0,9 than you most likely not using sufficient amount of nutrient solution. Forget about 20% runoff and water untill you see same EC numbers in and out. Anyway that 1,8 seems to be too high, I am observing tip burn with EC of 1,2 but it mainly depends on environment and phenos. Good luck!

 

[grou]

If your inflow is 1,8 and your runoff is 0,9 than you most likely not using sufficient amount of nutrient solution. Forget about 20% runoff and water untill you see same EC numbers in and out. Anyway that 1,8 seems to be too high, I am observing tip burn with EC of 1,2 but it mainly depends on environment and phenos. Good luck!

If your inflow is 1,8 and your runoff is 0,9 than you most likely not using sufficient amount of nutrient solution. Forget about 20% runoff and water untill you see same EC numbers in and out. Anyway that 1,8 seems to be too high, I am observing tip burn with EC of 1,2 but it mainly depends on environment and phenos. Good luck!

What ec do you recommend in this stage of grow (plants beginning to show preflowers)? Considering my tap ec is 0.25

 

[Rurumo]

I would say plants of that size don't need 1.8 ec. I'd lower it down to 1 and up to 1.2 when they get a bit more size. Plenty of runoff is a great idea, really fixes a lot of issues in coco.