I do have to ask, what do you mean by flushing? There seem to be different thoughts on flushing. In your 15L pots, how many liters do you run through it?
By flushing i mean i did not use nuts.
They got between 3 & 4 liter per pot when i meant flushing.
When i water normally it's always 2 liter per pot.
I still haven't fed them after that tho, still hesitating
I think it may be overwatering. The curled up leaves look like it. Your pots should feel really light before you water.
Read this thread over and over until you have it almost memorized
https://https://www.icmag.com/ic/showthread.php?t=241341
For some reason the link won't work but look at (a few things I learned growing coco dtw) in the coco section. H3ad goes coco is a good one too.
Then continue in some of the other coco threads the coco trees one is good also. After that you should have a firm grasp on coco. Also look at the coco chemistry one which will talk about the cat ion exchange of coco and how to charge and keep your coco with consistent nutrient delivery to your plants. You are growing Hydro so you need to think about it like that. Good luck.
I think it may be overwatering. The curled up leaves look like it. Your pots should feel really light before you water.
As far as those EC's being higher in runoff... you need less ferts as everybody has mentioned.
And also always calibrate your meters often. I do mine once a week.
Lastly if you store nutrient put an air stone in it.
Flushing is when you dump 2-3x pot size. That's why nothing is really changing. You are trying to flush out all the excess. 15L pot needs 30-45L of water to flush properly.
Also don't ever do straight water, you will throw off your caution banks. Cut nutes down to a quarter of what you have been currently feeding them. Once you get ec and ph coming out the same as what's going in then try a Ec of maybe 1.0 or so
Over watering young plants in coco will cause nitrogen lockout, and cause the plant to have a very wimpy root system.
I let the surface get a little dry before watering. By the time they go into flower they will need to be watered twice a day, and almost impossible to over water at that point, unless you have been over watering throughout veg. That is why air pots and smart pots are prefered. They help it dry out quicker and prevent root circling, by air pruning the roots.
Here is a master coco grower, explaining how to feed them. Skim through first 10 pages quick, which is mostly pictures. After that he explains using small containers to start, and wanting them to need to be watered, before feeding.
https://www.icmag.com/ic/showthread.php?t=300255
this seems to be interesting, i suppose this is what you wanted me to read..?
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1 is looking worse today, more droopy than usual, also branches of leaves looking redish:
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How high is humidity, and do you have good air circulation?? I just got f-ed over by Fusarium Wilt, which will manifest in bud rot a couple of weeks before harvest. Purpling of stalks and leaves, and yellowing early is a sign.