What's causing this? pics

Hello i have a buddy who is having some problems. These are all started from seed and approximately 2-3 weeks old. They have been transplanted into 5 gallon buckets a little over a week ago. They were looking good then almost over night problems started occurring. first noticed a few of the plants kind of yellowing out. Then a few contorted leaves. Then some burned tips. A few of the plants are fine with zero problems.

They are under an 8 bulb T5
temps in the low 70s
humidity around 45%
Advanced nutrients at half dose
here's the problem I'm thinking......he used promix that has been used before. It was used then thrown in a pile outside for a year so he figured it was good to go. Maybe there was still nutes left in the old promix? Old salts?
18/6 time
not sure on the strain but they are feminized.

any help is greatly appreciated.

thanks

Mag def, K def, and most likely caused by overwatering.

also check the ph it sat outside for a year so the buffer was most likely washed out of it.

i'm down with the mag def...not sure about the other things...1tbsp Epsom salts/gal water spray directly on leaves...also did u mix any lime in with that soil?

Thanks guys I'll have him introduce a little mag into the feeding and see if that helps.

dannyboy602 said:

i'm down with the mag def...not sure about the other things...1tbsp Epsom salts/gal water spray directly on leaves...also did u mix any lime in with that soil?

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No lime with the soil. Is there anything I can do now to make up for no lime in the soil?

Olive Drab Green said:

Mag def, K def, and most likely caused by overwatering.

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Just mag. No K def((this burning around the edges that looks like k def is basically mag def in high stages)).. Soil is dry..

Bub

Jeffro420 said:

No lime with the soil. Is there anything I can do now to make up for no lime in the soil?

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Add 0.7 grames for each 4 liters of water.

Jeffro420 said:

Is there anything I can do now to make up for no lime in the soil?

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I thought this was your buddy's grow? Or do you have special access to his pride and joy?

THCBrain said:

I thought this was your buddy's grow? Or do you have special access to his pride and joy?

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Thats not a brainer ha loooool

THCBrain said:

I thought this was your buddy's grow? Or do you have special access to his pride and joy?

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Lol it really is my buddys grow. I would never re use promix. He sent me the pics and is worried. I'm kind of helping him out getting started (only his Second grow). I usually don't run in to problems on my end but then again I buy new media and nutrients every time.