SOIL Leaves have dry dark brown and yellow edges, Curling under

[RobX117]

I have a couple of plants that are showing some weird signs that I have no idea what's causing it, I'm not sure if its humidity, nutrients or PH but they have dark brown and yellow edges on leafs with curling under
any help in the right direction would be nice, The plant on the far left is about to get pulled it was attacked by our house cat and never recovered,

using 2'x4'6' tent,
300 watt full spectrum mars hydro led light
18on 6 off currently,
Miracle Grow soil,
7 gallon buckets

Still need
fan,
exhaust setup,
cool air intake from under house

[Smokesteve]

Here is a good place to start. http://www.growweedeasy.com/nitrogen-toxicity-cannabis

[Campesino]

Agreed, looks like bad case of nutrient burn (Nitrogen perhaps among others). I don't like bringing bad news, but unfortunately, it is probably being caused by your soil. Miracle Grow soil is really inappropriate for cannabis because of time release nitrogen. What are you using for nutrients? Just the soil?
If it is bad like this during vegetative growth, the plants will probably not be able to be flowered in that soil.

[RobX117]

there is only one thing I know that could save these until my others catch up anyway.. I potted them in ph correct soil with no nutes, for the ones that are in toxicity I'm going to add some saw dust to them and some light water.. saw dust or any wood pulp such as mulch will use nitrogen up faster than the plant so it may balance it out I just didn't know what was the ailment thanks for the help if the wood pulp works ill post pics if not ill pull them and re do the soil and starts over

[Campesino]

Happy to help, and thank you for including all the pertinent info in your post.
I hope it goes well!

[RobX117]

I hope so too nothing else drives me mad like having to start over. If it works I'll type up a guide on it, ive been growing fruit trees and gardens forever with my family, just new to cannabis and definitely newer to indoors. Thanks again

[Campesino]

Cannabis will be most similar to plants like tomatoes. It is very sensitive to different nutrient loads during vegetative growth and flowering. Time release soils are great for other types of plants, but harmful to plants that flip into a flowering mode.
All the info you need to be successful with media and nutrients is in the main GWE site.