rusty spots and curling leafs

Light: 600watt Hps adjustawing
Fan: 6" Inline fan 400cfm
Tent: 4x4x6.5
Temp: 65-85
Humidity: 30-50%
Fetilizer: Biobizz
Setup: sog
ph: 6.8
EC: biobizz chart
Media: soil
Strain: jack 47 clones





Hello i have a sudden problem with my jack 47 plants,they are now 5 weeks in bloom and have started to getting rust spots and the leafs are curling upwards.
I have flushed the soil 3 days ago and the symptoms are getting worse by the day,i suspect i migth have been a little easy on the feeding since this is a sativa dominantstrain but never gone thirsty
Any one who know what to do,appreciate all help

Regards

i am leaning towards mag deficiency (but that is more hydro than soil) or your ph is off but u say it is 6.8 i would knock that down to 6.6 and see if that makes a dif.

ya up the micro nutes, cut back on Nitrogen if possible, those leaves are a little dark

do ya know the PH of the runoff?