afghan kush probs:(

hey ppl got some leaf probs thats just really sprung up over 48 hrs anyone got any thoughts would be appreciated, am planning flush with lime im reckoning mg prob??

info-
ok here we go, afghan kush fem 4 weeks veg gunna flower soon,
soil mg pottin mix/perlite have used b4 so i doubt its the prob i always tek out the shitty slow release pellets,
nutes biogro at 1ml/litre with bottled water of ph 7.4 soil ph at 6.5
feed every time pots dry which im wonderin whether i shud flush every other water,
temps are sweet bout 80 air circulations gud 400 hps with cooltube.
had no probs since my last waterin 4 days ago with 1.4ml bio gro then the problems started (was goin so well lol), ive included pickie of the overall plant has great sidebranchin! crap pictures tho sry,

Quick update just checked agen and now the effected leaf is crispin and shrivvlin???

too much nutes? leaves will get crisp if you overnute.
Possibly your PPM, will do this as well.

just gave em a gud flush with sum dolomite water should perk up hopefully its a kick in the balls when u got everything else to perfection and goin so well lol

a good flush with a little hydrogen peroxide for hte roots and it should snap back in two or 3 days

cheers for the input ppl
flushed yesterday and i reckon the plants looking pretty perky, fan leaves and growth seems to have improved slightly, im thinkin with the mg soil ferts and the ferts i was adding caused a nute lockout via ph or/and a buildup,
lets hope it doesnt return or get worse