Seedlings Looking Unhealthy - Help

Currently babysitting 3 seedlings for my father and one of which is displaying symptoms that the others aren't.
In the last 1-2 days this has happened:
- 2 bottom leaves are yellowing
- Top 2 are drooping.
- Zooming in you can also see there is slight darkening at all the edges.
- Growth stopped and falling behind other two.

6" net-pots / Hydroton / 2000W LED
Bottom 1.5" of net-pot submerged in water (total water depth in tray is 4")
24/7 gentle flow, not directly on plant, occasionally wet the surrounding rocks.
Have 2 fans circulating air
2 Air bubblers going around bases of plants.
Light schedule 18/6
Cannot currently see any roots coming out of net-pot
Rockwool cubes in hydroton

Temp at plants 80F
Water temp 68.5F
PH 6.1
Relative Humidity 50%
Tap water before adding nutrients 170tds
Added Flora-Micro, Flora-Grow, Flora-bloom (33ml/100L according to instructions)
Water after nutrients 325tds

So far I have -
Raised them up above water level for about 12 hours, no change so brought back down to 1.5" deep.
Emptied and mixed all new water, 9 hours later no change.
Raised PH from 5.5 to 6.1, 9 hours later no change.
Swapping positions with other plants in case it was air flow or positioning, 24 hours no change.

Really confused because the other two seem to be doing well, my father is adamant that they aren't overwatered because it's hydroton. Really desperate to get this thing healthy again.

Thanks!

I'd say yer drowning them

Water should be 1"-2" BELOW the bottom of the net pot, not above it
Bubbles are how they get wet

I'm not a fan of top feeding, adds to over watering

So a 6"+ net pot, in a 4" tray of water, open to the light, you will get goopies 100% that way

I take back what I said. Bad system, plants are starving

How much if each bottle you feeding them

You better get them things straightened out before pops gets home !

BobThe420Builder said:

I'd say yer drowning them

Water should be 1"-2" BELOW the bottom of the net pot, not above it
Bubbles are how they get wet

I'm not a fan of top feeding, adds to over watering

So a 6"+ net pot, in a 4" tray of water, open to the light, you will get goopies 100% that way

I take back what I said. Bad system, plants are starving

How much if each bottle you feeding them

View attachment 4785264

Click to expand...

Those numbers look higher than what I was following on the bottle.

Bottle is not what u want

Start at half strength, go from there

But they aren't getting water now, way to big of a net pot

BobThe420Builder said:

Bottle is not what u want

Start at half strength, go from there

But they aren't getting water now, way to big of a net pot

Click to expand...

So you think netpots should be brought above the waterline then?

And following the bottle instructions it has been given 2.5ml per 1G/3.79L per each bottle from the very beginning. You think this was too much or too little? TDS was brought from 175 to 325 with those amounts.

What do you think the main culprit was and what would you do now?

Added a pic of the bottom of netpot.

Thanks.

They aren't getting fed

To big of net pot

Empty the net pot, make sure the roots are at the bottom, fill in a bit of hydrotron

Drop water level 2" below net pot bottom so bubbles splash the bottom

And pray dad doesn't kick your asssssss


Edit


The water will get algie been exposed like that
Get a tub or something, not your Bath tub