yellowing leaves

I got these clones about two weeks ago. I came home this weekend and there was a bunch of dead leaves and dying leaves with brown spots.There is also still yellow leaves that just fall of when i touched them, so i pulled them all off. The remaining healthy leaves a little more light green. Do i pull of all of the leaves that are dying? More importantly, what is causing this? I gave them a bit of plant food 2 days ago but they still look pretty light green and a couple more leaves are still yellowing or getting brown spots. It has been in the 90's over the weekend so i was thinking heat stress? tell me what you think from the pictures. i also just started spraying them with CO2 a couple times per day about 5 days ago but don't think that would be it. I am a first time grower so any input helps. I have a 600w and a 1000w over 12 of them but the 600w is going to be removed to veg others when I flower these. Thanks! :rastasmoke:

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Were the clones already rooted?
What are you using as the source for CO2?
Looks like overwatering, but you should fill-out the troubleshooting form for a better diagnosis.

yes they were rooted. i am spraying them by hand twice a day for about 20 seconds with a co2 tank. i tried giving them a bit of nutrients in the last watering and i think it helped a little, but the coloring of the leaves are still very light green and a few random leaves are still yellow. I havnt watered them for 5 days because the dirt is still moist about 2-3 inches down and the leaves are hanging. I will fill the form out and water them tomorrow with just water.

Quote:

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Originally Posted by mlwjr69

i am spraying them by hand twice a day for about 20 seconds with a co2 tank.

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A 'quick' bump in CO2 might be a bonus...for about 10 seconds. After that, it mixes with ambient air, and the concentrations are watered-down with every cubic foot of fresh air from the intake.
But an over-concentrated dose might also fry the plants ability to 'breethe'. If you have no way to monitor ppm, I'd ditch the CO2 for now. At least till you get 'em healthy.
Read-up on the proper use of CO2 before continuing it's use.

Waiting for the form....