Any ideas anyone

Any idea what this is

yellowing of leaves...



need setup and routine info to help

600w hps in light mix soil 5gal pots nearly 4 weeks old temps around 27-28 degrees plenty of exhaust feeding with plagron nutes fed twice fairly lightly the others are fine it's only this one what has a problem my ph is around 6.7 it's a HSO blue dream thanks.

is it only on the bottom or on all of them?

Yeah just the bottom leaves

looks like you have a low nitrogen condition in your soil mix, if all of the other plants are fine just add some extra N when feeding and it should be fine.

its a cal/mag deficiency...

yeah could be N or cal mag

I shall add a bit of cal mag today to see if it sorts it self out if not I'll add some N next watering

I've watered with cal mag it doesn't seem to be stopping it's slightly spreading to the leaves above I don't think it's a n def I have a little bit of claw so don't think it's that my ph pen is fairly new so I don't think my oh pen is of what else could it be anyone

What dose did you give?

P or Mg def, most likely the latter. Clawing is N-toxic. Make sure your pH isn't off just to rule out lockout. Also, water droplets on leaves under bright light leaves spots sometimes, so be aware of that.

They are 4 weeks old added a dose at 1/4 strength 3rd week and the same 4th week I added a cal mag watering the other day and have added no nutes since I'm thinking now maybe just flush it all out and start again and I maybe need to calibrate my oh pen somehow to test its accuracy but my ph has always been 6.7-6.8

That's probably your issue. And why flush nutes that aren't there if all you added was CalMag?