Overnight disaster

Your plant is crying out for consistency. When the environment is all over the place (ph in your case) the plant will show a huge array of various issues and deficiencies.

For some reason, the first instinct people have will be; "oh, you're showing some mag deficiency here, or a nitrogen deficiency there" and they'll offer advice of chemicals, and nutrients, and additives to correct what they see as a deficiency. But it's just not the case, the plant needs to have a stable environment, otherwise you're simply nursing problems caused by poor environment, rather than fixing them.

Begin watering with the same ph, every single watering, don't try to over-correct a high ph, by watering with a ph that is too low. That's going to make matters worse before they get better. You're better off lowering it gradually, going from 7.5 to 7 on one watering, then to 6.5 on the next and so on, until you reach your desired ph, between 5.8 and 6.5 depending on the strain and medium.

If you had just a small 400watt hps, you could be back to that size plant or bigger in about 2-3 weeks from seed.. if that was my girl, and that happened only over night, I'd trash her and start over rather than try and repair the damage; those leaves won't go back to normal, you're now stuck waiting for fresh healthy growth. But that's just with my rooms and time frame, for you it may be worth it to keep her going.

What's she been fed so far if anything besides what's in the potting mix, and how old is she?

 

Are you sure that isn't the time release ferts in the Miracle Grow soil? It's known for burning plants and some times so badly that they don't recover. I'm not saying yours won't. I would transplant it to some better soil.

 

If the time release ferts in the soil were to have caused any burn, it would have been before last night. The plant would have been much more vulnerable to a burn as a seedling in that mix, and now it's been slowly depleting it.
When I used to grow a few canna plants in my extra household MG potting mix, in the empty spaces along side my other systems, I would begin feeding additional nutrient within 10 days of germination.

So I'm not sure why anyone would have burn issues from their potting mix, it's relatively weak (I used to drop seeds in, water, and let them go) and our plants can be very hungry when given the right care and environment.. it's more likely been a ph issue when the potting soil 'burned' plants in the past.

As I recall, I used to get about 3 oz's per plant in a 2 or 3 gallon pot of MG mix using hydro nutes.. just a bit of easy gravy, on top of whatever hydro or coco set up I had going on at the time. If I started extra plants, and didn't have the heart to toss them, in the MG mix they'd go.

Anyway she'll probably recover, just take good care of her, and give her the stability she craves. You could probably begin a very light feed schedule once you get this sorted, or even an 1/8th or 1/10th strength dose now.

 

You seem to know what you're talking about. Just heard so much bad about that MG, you know...

 

Yeah, apparently.

Here's a thread on that http://forum.grasscity.com/indoor-m...0-pgamg-pot-growers-against-miracle-grow.html

Good luck with your grow man.

 

MG is not the best medium or nutrient brand out there, of course, but in a pinch it will get the job done.

People have problems with all mediums, systems, and nutrients when they first start out, they then blame inexperience on the tools they're working with.
If any of those folks who failed when trying MG products kept up with them, they'd eventually learn how to use them just like any other product or brand. When you grow in coco and MG potting mix, side-by-side, coco specific nutes in the coco, MG nutes in the MG mix, the end results are visually hardly any different, just so long as you kept up with their specific environmental requirements.

The main difference I find, is in the end quality of your smoke; it always tastes better when you give in, and shell out the extra few bucks for better brands. Using MG soil, and your favorite brand of organic or hydro nutes, is a start.

I wouldn't flush just now, unless you very recently gave them too much of something (too much fert, or ph Up or Down); your plant is in a weakened state, and it may not recover as quickly if she's kept too wet. Just begin slowly lowering her ph to a healthy level, if it's as high as you say.
If you do get some run off, collect it as cleanly as possible (without allowing it to touch anything but the cup you're collecting it in as it drips out), and see how the ph is doing on its way out.