OK let's get serious for a moment. MG is not the soil of choice for cannabis growers. But it can work. This is obviously someone who doesn't have the resources many here happen to have. So why not help him? He can begin to work toward optimal his next grow or two.
Let's rescue his grow ok? First he needs to NOT flush he's in moisture control so he will drown that plant if he flushes. Next it's not a Ca/Mg deficiency that happens in the middle of the plant and it is rounder more punctate, rust colored spots. He's both Nitrogen and Potassium deficient.
Time to give that plant a feeding and not overwater. We actually happen to have a guy with a Ph.D. in Biochem who works these boards maybe he will deign to offer the kid some advice on a good nutrient.
I grow completely hydro (coco coir + perlite) and prior to that I ran solely rails (NFT-nutrient film technique). So my nutrient suggestions are hydro focused but very flexible so they would work and they are relatively cheap in the world of cannabis specifics.
Fox Farm has several problems and I agree with Dr. Who not to use it but again I know little about actual soils and the microbiome.
If he pots up I'd go Coco and move to General Hydroponics three part FloraMicro, FloraGro, FloraBloom and add GH's CaliMagic (better Ca to Mg ratio). As for best nutrient ratio let's ask
@Bob Zmuda who grows like a gangster what he'd use to get this kid
@Deondre to the finish line. Another couple gangsters of growing here are
@Gary Goodson and
@Diabolical666 if anyone can help this kid save his grow they can. BTW
@mr sunshine actually can grow most anything anywhere but I don't know if the bird will help after such idiocy.
@cannabineer you have a Ph.D. in Organic Chem would you like to wax poetic on nutrient ratios? (when you get done teaching that summer school class LOL)
He's not using lights and is carting the plant in and out every day so I'd hold it's growth in what it's in and finish it. Otherwise he risks breakage.
DISCLAIMERS: I am merely an intermediate grower with zero claim to fame. I focus solely on pheno searching and breeding. Use my grow advice at your own risk.