Very sick babies

Hey everyone, thank you for taking the time to read my post and giving some advice!

i have these young plants that developed brown rusty spots very quickly and it has developed into this over the last 2 days.

Room info:
Aeroponic system feeding 15mins on/30 mins off (ordered a better digital timer to have more frequent on/off times)
2.4x2.4 tent
Under 4x 600w lights around 1.5 meters above canopy, air cooled
Temperature always 25C in day time, 19C night time
Set to 20 hours on 4 hours off
Humidity ranges 55-60% always
Plants are 9 days old
Germinated in wet tissue paper, transferred to root riot cubes then into the aero system with clay pebbles.
Started them on Formulex at 0.5ml per litre for the first 4 days (EC 0.6) until they were put into the aero system, at this point they all looked great and healthy.
then went on to GHE (terra aquatica) 3 part feed on their first feeding schedule called “first roots” this brought the EC to 0.6
PH has always been 5.8-6.0 throughout their whole life
After 3 days I noticed little brown rust spots on the leaves, companied with leaves dropping. I thought this was because the EC was too low and maybe they had a deficiency. So I upped it to 1.2, on the feeding schedule “first true leaves”
The rust spots have developed into almost full browning on some of the worst plants, along with twisting/curling of the leaves which I know is I sign of over feeding.

these pictures are of the worst examples. What do you think the problem is here?

These first 4 pictures are at day 6

These pictures are at day 9

You're overfeeding and overlighting tiny plants.
4x HPS overtop of plants with only one set of true leaves? 1.2 ec is crazy high for tiny plants. Even .6 is too high imo. Tiny plants need very little food.

Jjgrow420 said:

You're overfeeding and overlighting tiny plants.
4x HPS overtop of plants with only one set of true leaves? 1.2 ec is crazy high for tiny plants. Even .6 is too high imo. Tiny plants need very little food.

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1.2 EC is crazy high? The feeding schedule says this is what the EC should be for first true leaves, this is in aeroponics so there is no other medium to provide nutrients. Also for formulex baby food goes to 0.6 EC

Do you think this is burn from the lights? They are all the way at the top of the tent, around 1.5 meters from the top of the plants

How big is the grow area?

Nope_49595933949 said:

How big is the grow area?

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2.4 meters by 2.4 meters

abfigos said:

2.4 meters by 2.4 meters

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I'd say that's probably too much for seedling but once they get going that should work well.

Nope_49595933949 said:

I'd say that's probably too much for seedling but once they get going that should work well.

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You mean too much light? Any idea what caused this problem?

abfigos said:

You mean too much light? Any idea what caused this problem?

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I don't grow in this method but guessing nutes and too much light. I wouldn't take my word for it though.

At that stage they need very little light and nutes. My cuttings grow better in just tap water on a window sill.

abfigos said:

1.2 EC is crazy high? The feeding schedule says this is what the EC should be for first true leaves, this is in aeroponics so there is no other medium to provide nutrients. Also for formulex baby food goes to 0.6 EC

Do you think this is burn from the lights? They are all the way at the top of the tent, around 1.5 meters from the top of the plants

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1.2 ec for a plant with 2 leaves is crazy high yes.

Too much light.
Too much nutrients.

What is your ppfd? Check it )they really need around 150-200 ppfd in seeding.if ppfd is okey i would say your nutrient uptake has some issues.1.2ec is too high for her as well.around 0.5 max in that stage i would say

abfigos said:

The feeding schedule says this is what the EC should be for first true leaves

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I would not call anything there true leaves. They are pretty badly nutrient burned.
Starting over would be the route i would follow

Boatguy said:

I would not call anything there true leaves. They are pretty badly nutrient burned.
Starting over would be the route i would follow

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I would keep her just go with plaint phd water and some little calmag in it!sometimes sick plants can outgrow healthy plants

Dext3r said:

I would keep her just go with plaint phd water and some little calmag in it!sometimes sick plants can outgrow healthy plants

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Yep, can't forget a good 3 part calmag.

Dext3r said:

I would keep her just go with plaint phd water and some little calmag in it!sometimes sick plants can outgrow healthy plants

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OK... It is just that within less than 2 weeks he could have new plants larger than those he is trying to save.
I currently have some 13 day old plants in soil that are well ahead of what is going on there. They were also burned, but not to the same degree because i skipped the seedling mix.

1/4 strength nutrients for now and then slowly increase the EC as the plants get bigger..

If you're using tap water there is already going to be more than enough Ca and Mg. Don't give just calmag. You don't want to give just those two nutrients. You want a complete nutrient profile just at a much lower EC. NPK is going to be more important for the plant than Ca and Mg. That's why they're called macronutrients as they're the 3 most important for plant growth. The 3 part GHE is going to have all the Ca and Mg needed. Calmag is the most overused and unnecessary additive there is. Unless you're using RO water there is rarely a need for it.

Good luck.