Plants dying beginner please help!

1) started as white powdery substance on side of rockwool cubes
2) next the leaves started to turn silver
3) now some leaves near the bottom are turning yellow and dying

I changed the nutrients to include 5.5 ml (aquaflakes A&B), root excelerator, liquid karma, and multi zen. switched from MH lamp to fluorescent, increased air flow, tried spraying the leaves with 1:9 skim milk soln and 1:4 hydrogen peroxide...nothing has worked. does anyone know what this can be? this is first grow could really use some feedback. these are zambezi autoflower strains
Is this a nutrient or pest problem?

Note: leaves are turing yellow from the topmost leaves from the middle to the exterior, i clipped some of the leaves that were dying in an effort to spread any contagion

Thank you friends and best of luck with your projects, peace

View attachment 3029106View attachment 3029107View attachment 3029108View attachment 3029109

Do not triple post shit...I will not help you for that..two and I would have helped you and explained that that's frowned upon and annoying, three and you just get the explanation with no help...

I can't see pics at the moment.
But im sure some one will show up.
But posting the same thing in multi places is a bad idea for a few reasons.
1 Its considered spam.
not that im perfect
2 it means you have to go 4 places to get your answers.
3 its annoying to answer some ones question when Three other people have
already answered it.

Alot of the people who like to help scan
the forum and will see you.

Good luck man

...ok ill be nice...i don't grow in pellets or hydro but it looks like nute burn and in soil that would be way too early to feed though I do know you need to supplement earlier with hydro..still, looks to be nute burn

Also if you notice your tips are browning, if that happened just before our around the same time that solidifies that its nute burn because tip burn is the first sign to let off on the nutes for a bit

when you aSK for help include details, no one can help without them. soil type, nutrient line, age of plant, soil ph and ppm, what ph and ec do you feed at, ect. and yes nutrient burn. if its a hot soil its to much for a seedling, if its not and its all u just feed them plain water, un ph'ed and watch for new growth. those affected leafs r gonna die no matter what

With no details.... I would guess you are overwatering.. are you using an aero-feeding schedule. if so those pebbles and rock wool could be causing root rot. Can probably still save them at this point if thats the case but, I dont think it'd be worth it unless you got some good genetics.

sorry for the spam, my OCD just made me worry apoligize will not happen again
nutrients are:

Aquaflakses A &B 3.5 mm per gal
multizen
nitroboost 1 mm per gallon
root excel .5 mm per gal
liquid karma

plants are sitting in a 4 gallon tub...
if you need any additional info please let me know thanks again

i just raised the water level so the roots are not more into the water and added 1ml of nitroboost per gallon, should i spray the leaves with magic green to reverse the lock out?

pH is btwn 5.5-6, light orange/yellow on the ph test kit

what's the ppm

You burnt her. The plant is going to remain in shock for a couple days to a week or two. Use plain water you will want to ph. If you want you can cut the burnt tips to ease the pain. Don't get over anxious to feed at such a delicate stage. At this stage you want to focus on building healthy roots so that when you do feed you will get maximum results. Remember when feeding start easy if you start heavy you can never go back.

Cutting the leaf tips will do you absolutely no good while possibly reinjuring the plant and they won't "stay in shock for days or Weeks" that's a very over used phrase with marijuana growers but the rest is on point^..but ya its all good don't worry about deleting the extras they will just die in obscurity lol and if you just give it the basics your plant will perk right back up