Fan Leaves Dying!

Got a problem with my northern lights, took them as cuttings, grew nice and well for 2 weeks, put them into bud they started to hair up nicely then they suddenly took a dive all the leaves started to show a mag def, so i gave em some epsom and made sure my temps were ok, they are 18.6lowest at night, and about 23 in the day, using biobizz according to their schedule, in a standard multi purpose compost from wilkos, currently under 250w hps with a 125mm exhaust fan and passive intake, after giving them a good feed i expected to see a marked improvement but the fan leaves are just dying off, any ideas??

Looks like it's lacking in Mg Fe and Cu. I would check your water source. Most times if you are using RO water or distilled you are going to need to suppliment it with CalMag or something to bring the ppm back up.

I had a Mg deficiency for about a week when I used bottled gallons of water to water my plants. I also use BioBizz. I needed some gallon containers and figured not to waste the water in them, so I used it to feed my ladies.

After about a week they were showing signs, bottled water ran out, and about 5 days or so later after returning to my tap water with a ppm around 250 it cleared itself up. Found out after testing that the bottled water was about 4 ppm.

Lesson learned.

You will probably need to fill out a troubleshooting form, its in the top of the plant problems forum I believe, and I'm sure plenty will chime in for you.

Overapplication of magnesium sulfate will cause nutrient lockout.
Have you read the epsom salt sticky?

Epsom salts not a miracle cure...