OK...im propper panicking now..take a look at these pics.

I raised the nute level to..

30ml grow
20ml micro
10 ml bloom

PH has been kept between 5.5 and 6.2

As you can see, they are starting to get very yellow on the tips and side margins..and some are showing chlorosis in the inter veinal areas.

Looking like either Zinc, Iron or Magnesium deficiency.

How can this be when all the various nutrients are available and the PH is fine ? I have ruled out heat stress too as i have a coolshade lamp.

I have been using the PYTHOFF too.

Any opinions would be greatly appreciated.