Plant Problem, Can Anyone Help?

About half my plant have the problem pictured below, it started at the bottom and working its way up it been there for a week now.
I have 30 plants 3 weeks into veg growing in 10L pots with terra pro soil under 6x 600 watt lights, feeding them canna vega and hygrozyme, PH is 5.8 temps are 84f day and 78f night.

Cheers in advance

It looks like a pH issue to me.
Have you calibrated your pH meter recently?

cant rule out nitrogen burn

Nitrogen burn would be much darker wouldnt you think?

i to did think it was a p.h issue, PH pen was last calibrated 8 weeks ago.

I check mine every couple weeks. Its usualy off. May be that.

hi everyone i kinda have the same problem
my plants are about three weeks old and i use the hydro method
my ph is 5.8 and ppm is 700
this problem occured when i was using the dutch master formula calculator
i followed the measurements for my crops but didnt realize it was the totaled mixtures for the plants
i was using just grow gold A & B and the ppm was 900 i notice a day later my leaves started to burn
i tried to flush with it didnt do nothing my plants seems worser
can anyone help out please

bio terra plus is a very rich organic soil....... u might wanna not use too much ferts in it until flowering.... i think its a ph problem along with too much Nitrogen......
Good luck
peace out

Flush the plants through it may be a salt or onother build up from the feed,flush the plants and i'm sure that they will pick up.look for a new feed with a high n.p.k.take all the yellow leaves off this may make the plant look bare but they are no use to the plant anymore.and see if all the new growth goes the same i would let dry then rewater has well this could be a root rot issue if you have bombarded the plant with water.

tested my PH pen today it was 0.4 out, not much but enough to start problems.

jahtrip, thanks for the info, i used terra pro on my last grow with now problems, it seems now i am using canna nutes it does not do it justice

so should i cut off all the burned leaves?
and when is a good time to flower them its been a month since i germated

There is a good thread on what to do here

Its pretty much everything about ph

what happen if my seeding leaves are burned too
theyre bearly a week old and started to have burnt leaves
should i cut off the burned leaves just like my older plants?
dang i thought growing weed would be easy its just the opposite
can anyone help out thanks in advance